The expression which relates the total time taken and the time taken for the trip is [15s + 15(s+2)] / s² + 2s and 2.32 hours respectively.
Travel time = distance ÷ speed
Second half of the trip :
Time taken for second half of trip :
Time taken = 15 / s
First half of the trip :
Time taken for first half of trip :
Time taken = 15 / (s+2)
Total time taken :
First half + second half
15/(s+2) + 15/s = [15s + 15(s+2)] / s² + 2s
B)
If s = 12
Substitute s = 12 into the expression :
[15(12) + 15(12+2)] / 12² + 2(12)
[180 + 210] / 144 + 24
390 / 168
= 2.32 hours
Therefore, the total time taken is 2.32 hours.
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