Item 19 the area of the parallelogram is (4x+16)(4x+16) square feet. write an expression for the base.

Knowing that A=lw; 

We know that the length and width are multiplied together to give the area; since we are given 2 exactly same terms multiplied together, we can assume that one of them is the base. 

Therefore, the base expression would be (4x+16). 

Hope I helped :) 

All you have to do is multiply