The Formula P=2l+2w relates the perimeter P of a triangle to its length l and width w. Solve this formula for w

Question

The Formula P=2l+2w relates the perimeter P of a triangle to its length l and width w. Solve this formula for w

Answer 1

Here is a step by step breakdown : 

P = 2l + 2w 
P -2l = 2l + 2w - 2l      ( subtracting 2l from both sides ) 
P - 2l = 2w       ( because 2l - 2l = 0 ) 
or 2w = P - 2l 

Therefore, w = (P - 2l ) / 2   ( dividing both sides by 2 )