3c to the 3rd power +2c squared -162x +81

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?

Jacob signs up to work for 2 1/2 hours at the school carnival. if each work shift is 3/4 hour, how many shifts will jacob work? (i just want to double check : |, for anybody that responds! : )

True or false look at the picture pls : /