1.) First, you use the formula for finding the simple interest, which is I = Prt
I = PRT
I = 5,000 x 0.09 x 5
I = 450 x 5
I = $2,250
2.) Since it says 1 year instead of 5, you multiply 450 by 1. So she only pays $450. To get how much money she'll save in interest, you subtract 2,250 by 450, which equals 1,800. So, she'll save $1,800 in interest.