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

Answer:

30 miles/hr

Step-by-step 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