Question 1079197
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Let u be the rate of the boat in the first 5 hours.
Then the rate of the boat is (u-4) in the last 3 hours.

Your equation for u is the "distance" equation

5u + 3(u-4) = 132.

8u - 12 = 132  --->  8u = 132 + 12  --->  8u = 144  --->  u = {{{144/8}}} = 18.

The speed of the boat during first 5 hours was 18 miles per hour.

Hence, it covered the distance of 5*18 = 90 miles during the first 5 hours.
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