Answer
Zak will catch Connie after 5 hours.
Work Step by Step
Let X represent the time it will take Zak to catch Connie.
Connie rides at 10 miles per hour. Because she leaves an hour earlier than Zak, by the time Zak leaves, she will be 10 miles ahead of him.
So Zak, who rides at 12 miles per hour, is at a 10 mile disadvantage. Because they will both have covered the same distance when they meet, we obtain:
12X = 10X + 10
2X = 10
Divide both sides by 2
.
X = 5
Zak will catch Connie after 5 hours.
