Algebra 2 Problem
posted by Isabella .
The sides of a rectangle have lengths x+9 and widths x3. Write an equation that describes the perimeter, P, of the rectangle in terms of x.
I do not understand this problem, could someone please help me?

Perimeter = 2(width) + 2(length)
= 2(x3) + 2(x+9)
= .....
expand, collect like terms and simplify