If i had 5 pops and my friend toke 3 how much would i have left?

Quick translate "x is 12 units from 20" into an equation. what are the values of x being described? if you can answer any of my other questions that'd be great too

The standard distance between studs in a house is 1.5 feet. if you have a set of blueprints for a house that mark every 1.5 feet with 2 in., by how many inches will a 13-foot wall be represented?

Subscriptions to a popular fashion magazine have gone down by a consistent percentage each year and can be modeled by the function y = 42,000(0.96)t. what does the value 42,000 represent in the function?