Answer:
The expression that represents the perimeter of the rectangle is "12*x + 18", where "x" is the length of the rectangle.
Step-by-step explanation:
In order to solve this question we were given an expression that relates both dimensions of the rectangle. This expression in a mathematical form where "x" is the length and "y" is the width is shown bellow:
y = 9 + 5*x
The perimeter of a rectangle is given by:
perimeter = 2*length + 2*width
perimeter = 2*x + 2*(9+5*x)
perimeter = 2*x + 18 + 10*x
perimeter = 12*x + 18
The expression that represents the perimeter of the rectangle is "12*x + 18", where "x" is the length of the rectangle.