Question

Elaine drives her car 70 miles and has an average of a certain speed. If the average speed had been 3mph more, she could have traveled 77 miles in the same length of time. What was her average speed

Answer 1

30 miles/hr

Explanation:

d / r = time distance divided by rate = time

70 / r = time and 77/(r+3 ) = time r = her original average speed

'time' is the same for both so we can equate the equations

70/r = 77/(r+3) cross multiply

70r + 210 = 77r

7r = 210

r = 30 m/hr