SOLUTION: A salesman drives from Ajax to Barrington, a distance of 120 mi, at a steady speed. He then increases his speed by 15 mi/h to drive the 163 mi from Barrington to Collins. If the se
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Question 1166481: A salesman drives from Ajax to Barrington, a distance of 120 mi, at a steady speed. He then increases his speed by 15 mi/h to drive the 163 mi from Barrington to Collins. If the second leg of his trip took 3 min more time than the first leg, how fast was he driving between Ajax and Barrington? Answer by ikleyn(52814) (Show Source):
From the condition, you have this "time" equation
- = , or
- = .
where x is the average speed under the question, in miles per hour.
To find x, first multiply both sides by 20x*(x+15); reduce it to the standard form quadratic equation and then solve it.