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You just left for vacation 2 hours ago. You have driven about 50 miles per hour on the 2-lane road and take an exit to get dinner. You call your Dad to check in. Your Dad has decided to join you after initially turning down your invitation. How long will you have to wait for him if he drives 40 miles per hour?

A 2 hours + 30 minutes
Explaination
The formula for distance travelled is: Distance travelled = Speed x Time Hence, the distance you have travelled is: D = 50 miles per hour x 2 hours = 50 x 2 = 100 miles The time needed by your father to cover the same distance at slower speed is: 100 = 40 x Time needed Time needed = $5465_w27_h38.png$ = 2.5 hours, or 2 hours and 30 minutes TIP: It is easier to remember the formula as: D = ST
B 2 hours + 20 minutes
C 2 hours + 40 minutes
D 3 hours