Question 1109901
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Nancy had to drive only 2 hours to catch up to Bobby, who drove for 5 hours.  Since the distances were the same and the ratio of times was 2:5, the ratio of speeds was 5:2.<br>
Let Bobby's speed by 2x and Nancy's speed be 5x.  Nancy's speed is 42km/h faster than Bobby's:
{{{5x-2x=42}}}
{{{3x=42}}}
{{{x = 14}}}<br>
Bobby's speed was 2x = 28km/hr; Nancy's was 5x = 70km/hr.