Math
posted by Donna .
How do I write a polynomial expression to represent the third side of the triangle? I know one side is 2x3y and the other is x+2y and P=5x+2y? I am lost.

I will assume that P represents the perimeter.
Let the third side be S
S + 2x3y + x+2y = 5x + 2y
S = 5x+2y  2x + 3y  x  2y
= 2x + 3y
check:
What is the sum of (x+2y) + (2x3y) + (2x+3y) ??