Distance word problem

Question

Aaron and Jessica walked to the dock at 2 miles per hour, jumped into the boat, and motored to Denver at 46 miles per hour. If the total distance was 21 miles and the trip took 5 hours in all, how far did they go by boat?

Answer 1

d= time times speed

2(5-b) +46(b) = 21, b= time going 46 mph, 21-b = time going 2 mph

46b-2b = 21 -10

44b =11

b = 11/44= 1/4 hour by boat

5-b = 21-1/4 = 5-1/4 = 4 3/4 hours walking

d = 46(1/4) = 11 1/2 miles by boat

w = 2(4 3/4) = 9 1/2 miles walking