Step-by-step explanation:
Price of CD = $13.59
The coupon is worth = $1.85
Amount he pays with = $20
The exact cost of the CD = Price of CD - The coupon is worth
The exact cost he is to pay for the CD = $13.59 - $1.85
The exact cost he is to pay for the CD = $11.74
The change he gets = Amount he pays with -