Question 344790
Wilma drove at an average speed of 35 mph from her home in City A to visit her sister in City B.
She stayed in City B 20 hours, and on the trip back averaged 60 mph. She returned home 41 hours after leaving.
We have to determine how many miles x is it from City A to City B.
1. In terms of x, express Wilma's driving time from A to B
:
We are only interested in the driving time which is: 41 - 20 = 21 hrs
:
Write a time equation:
total drive time = time there + time back
t(x) = {{{x/35}}} + {{{x/60}}}
:
t(x) = 21 hrs
Find x
{{{x/35}}} + {{{x/60}}} = 21
Multiply by 420, results
12x + 7x = 420(21)
19x = 8820
x = {{{8820/19}}}
x = 464.2 mi from A to B 
:
:
Check this find the time each way
464.2/35 = 13.26 hrs
464.2/60 =  7.74 hrs
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total time: 21 hrs; confirms our solution