Online calculator

Hello, while creating a calculator, I encountered a problem with the formula. I need it to calculate like this:

file script.js

price = (typ*L+L+B)*H;

if in numbers, it would be like this: price = (0.5*4+4+6)*2.4; the answer gives 20

but the operation typ*L is not executed, as I understand the same parameter cannot be taken again?