Order of operations means you do less lines of code.
meal = 44.5
tax = 6.75/100
mealtax = meal*tax
The above is the same result, more lines of code. Order of operations for math is a constant. It is the same regardless of language so they use it to make the code simpler. Without it code becomes longer and more drawn out, which isn't needed. I know it doesn't seem useful in 7 lines of code, but imagine 7000. If this were code on a website like this one with hundreds of hits per minute, reducing the amount of code to run, or amount of JS to transfer to the client by every byte helps.