Express 5^20 as a power of 25

The area of a rectangle is 15+5y square feet. which of the following expressions could be the length of the sides of the rectangle, in feet a. 5 and 3y b. 5 and 3+y c. 5 and 5+y d. 3 and 5+3y

How do you determine whether a relationship represented as as graph is linear or nonlinear

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)