I need an alternative to the higher maths for my homeschooled high school child.?

Just continue with a life skills approach. Some of these things might require the math you are avoiding to some degree.

For example if you are measuring a room for carpet or wallpaper, that is geometry.

Algebra Theory (followed by building) of radios and any other electronics equipment, astronomy, cars, airplanes, bridges, …just about anything
in industry. Even in sewage plants; it helps to understand rates of bacterial growth …. Banks operate on mathematical theory, not just
money calculations using the binomial theorem etc., but theories of economis and mathematical models. Industrial engineers use algebra (among other tools) to design the machinery to make just about everything you see on the store Shelf

Let’s say that you’re currently fourteen and that you want to save enough money to buy a car from a neighbor that’s willing to sell it to you for
$2000 when you turn sixteen. If you can get a job when you turn 15 making $5.25 an hour (and recognizing that Uncle Sam is probably going to hit you for 7.65% (?) for Social Security but you should be tax free other than that) and you will be able to work 10 hours a week for nine months of that and 30 hours a week for the other three, what percentage of your take-home pay do you need to save in order to pay for the car – or will you have to make additional money mowing lawns or delivering papers?

I could come up with loads of other “around-the-house” examples including figuring out how much material you need to build a deck or a fence or
finish the basement. These can also involve geometry and trigonometry. If you need to build a fence around your back yard that is 80 feet by 40 ft and your house is 60 feet wide and centered on the lot, how many cubic feet of concrete do you need to purchase if the post holes are going to be spaced eight feet apart, are going to be one foot in diameter and 18 inches deep and the posts are 4″x4″ (actually a little smaller than that) and will sit in the bottom of each hole?

The truth is that algebra is so pervasive that most children are able to solve simple algebra problems without even realizing that that’s what
they’re doing. The first time a kid figures out how much candy he can buy with the money he has or how much more money she needs to buy that toy she wants they are using algebra – but they are using it on a sufficiently small scale that they can skip the formal steps needed for solving more
involved problems.

So I would not worry about calculus, but do at least a little geometry and finish up the algebra. After that fodus on using it through things you do. Let him build something from wood and design it himself. He has to measure it out and decide how much supplies to buy. And make a budget. You can start with something small like a bird house or tray feeder and work your way up to other things if he shows an affinity and interest.
If he doesn’t like building, let him plan a flower bed, same kind of measuring and budgeting. Work with him when things go wrong around the house or repairs are being done. MAybe start repairs you have been meaning to get to because you can turn it into a lesson.

Plan a vacation, even a small one and let him do the budgetting (with your supervision)

Start focusing on money management. So many kids have no idea how devistating credit card debt can be or how much stuff costs. Work with him on learning how much a certain amount of debt costs at 20% interest each year. Let him sit with you during the paying of the household bills. Practice balancing a pretend checkbook. Help him learn to use computer programs like quicken.

Work on learning computer like excell, power point, programs that are used in most businesses and lack of knowledge could cost him a job of his choice.

Work with him on cooking. Lots of measuring there and he needs to know what he is doing to feed himself healthy meals.

Use math, science, and anything else you don’t feel like needs a full curriculum to teach him how to be a self sufficient man. One that takes pride in what he does and is not afraid to get a how to book and figure out something new. One that knows how to change the oil and wallpaper a bathroom. He and his wife will thank you.

Good luck,