One morning, John drove 11 hours before stopping to eat.After lunch, he increased his speed by 10 mph.If he completed a 730-mile trip in 14 hours of driving time, how fast did he drive in the morning?
A)53 mph
B)43 mph
C)50 mph
D)46 mph
E)58 mph

Question

Quizplus · Accepted Answer

Let x be the speed in the morning. Then,
11x + (730-11x)/(x+10) = 14
Simplifying the equation, we get:
11x^2 + 40x - 7300 = 0
Solving the quadratic equation, we get x = 50 or x = -66.36
Since x must be positive, the answer is x = 50 mph.

One Morning, John Drove 11 Hours Before Stopping to Eat