In this problem, we are looking for the total inches of ribbon that Risa needed in order to complete sewing all sides of the Blanket.
She needs 72 inches per sides of the blanket.
A blanket is consisting of 4 sides, therefore multiply 72 by 4.
=> 72 x 4
=> 288 inches
or simply add 4 72s
=> 72 + 72 + 72 + 72
=> 288 inches