Simplify sin^2y/sec^2 y−1 to a single trigonometric function

Horace's speedometer reads 60 miles per hour, but during a road test he finds that he was actually driving 58 mph. what is the percent error in horaces speedometer?

What adds to be the bottom number but also multiplies to be the top number with 8 on the bottom and 15 on top

Use the squared identities to simplify sin^2x cos^2x