Question

One morning, Justin drove 3 hours before stopping to eat lunch at Chick-fil-A. After lunch, he increased his speed by 10 mph. If he completed a 530-mile trip in 8 hours of driving time, how fast did he drive in the morning?

Answer 1

Answer:

60 miles per hour

Step-by-step explanation:

Let x represent Justin's speed in the morning.

We have been given that one morning Justin drove 3 hours before stopping to eat lunch at Chick-fil-A.

$\text{Distance}=\text{Speed}\times \text{Time}$

Distance covered by Justin in 3 hours would be $3x$.

After lunch, he increased his speed by 10 mph; so his new speed would be $x+10$.

We are also told that he traveled 530-mile trip in 8 hours. The time he drove after lunch would be $8-3=5\text{ hours}$.

Distance covered by Justin in 5 hours after lunch would be $5(x+10)$.

Now, we will equate distance traveled before and after lunch to solve for x as:

$3x+5(x+10)=530$

$3x+5x+50=530$

$8x+50=530$

$8x+50-50=530-50$

$8x=480$

$\frac{8x}{8}=\frac{480}{8}$

$x=60$

Therefore, Justin drove at a speed of 60 miles per hour in the morning.