What is the length of DE?

A.7
B.5
C.8
D.6

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )

Study results indicate that the mean length of time people spend on a bus in a city is between 21.2 min and 24.5 min what is the study margin of the error?

Marco states that 7.696696669…… is a rational number because it is a repeating decimal. is he correct? justify your answer.