Jack drove to work in the morning at an average speed of 45 miles per hour. He returned home in the evening along the same route and averaged 30 miles per hour. If Jack spent a total of one hour commuting to and from work, how many miles did he drive to work in the morning?

Step-by-step explanation:

Let's say that the time it took him to get to work in the morning is  t hours. Then the time it took him to get home in the afternoon must be 1 - t hours. We know that for any trip, distance equals rate times time or d = rt . That means that the distance he drove to work is given by , but we also know that the distance he drove to get home must be the same distance, because he took the same route (and, presumably, no one picked up him house and moved it while he was at work) so for the trip home we can say  d = 30 × (1 - t) and since the distances are equal, we can say: 

45t = 30 × (1 - t)

45t = 30 - 30t

45t + 30t = 30

75t = 30

t = 30/75

t = 2 /5 hour to drive to work at 45mph

Since ,  d = rt

d = 45 ×(2/5) = 18miles

b

step-by-step explanation: