My homeschooled son is stuck on a few problems and I'm hoping that you can help me help him. Here are the problems, can someone explain to me the logic/forumula behind them? Answers are in parenthesis, however we need help understanding how they got to the answer.

You are going on a trip to the Natural History Museum. AT 9am you leave for the museum, which is 120 miles away. At 10:15 you are 63 miles away from the museum.

:: Write a linear equation that gives the distance d (in miles) from teh museum in terms of the time t. Let t represent the number of minutes since 9. (d= -0.76t = 120)

:: Find the distance you are from the museum after you have traveled 2 hours. (28.8 mi)

:: According to your equation, when will you reach the museum? at about 11:38 AM

A mountain climber is scaling a 300 foot cliff at a constant rate. The climber starts at the bottom at noon and by 12:300 the climber has moved 62 feet up the cliff.

:: Wrie an equation that gives the distance d (in feet) remaining in teh climb in terms of the time t (in hours). What is the slope of the line? (d = -124t + 300)

:: At what time will the mountain climber reach the top of the cliff? (at about 2:25 pm)

Thank you for any help that you can provide.