What makes the statement true? -3 – = 6

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

Each of the walls of a room with square dimensions has been built with two pieces of sheetrock, a smaller one and a larger one. the length of all the smaller ones is the same and is stored in the variable small. similarly, the length of all the larger ones is the same and is stored in the variable large. write a single expression whose value is the total area of this room. do not use any method invocations.

What expression is equivalent to 42x-56y