Question 903490
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While a solution using formal algebra is probably wanted, note that solving the problem informally, using logical reasoning and simple arithmetic instead of formal algebra, provides good mental exercise.<br>
The two cyclists cover the total 90 miles in 3 hours, so their combined speed is 90/3 = 30 mph.<br>
If they were cycling at the same speed, each of them would be going 30/2 = 15 mph.<br>
Starting from that point in the reasoning, to make their speeds differ by 8 mph we need to increase one speed by 4 mph and decrease the other by 4 mph.<br>
ANSWERS: 15+4 = 19 mph and 15-4 = 11 mph<br>