Question

A= P + l solve for l

Answer 1

When you have an equation and needs to solve for a variable, you need to clear that variable, as follow:

$A=P+I$

you need to see what is with the variable I. In this case is the P so you can clear the I by subtracting a P from both sides of the equation:

$A-P=P+I-P$

You make the subtraction (P-P=0) and you get:

$A-P=I$

Then so, the solution for I is:

$I=A-P$