Question 838771
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Hi
If car B travels 10 mph faster than car A speed {{{highlight_green(x)}}}
& Car A travels 120 miles in the same time that car B travels 150 miles
Note:  D = rt   0r t = D/rate
Question states***
  {{{120mi/x =  150/(x+10)}}} ***  |Cross Multiplying to solve
  120(x+10) = 150x
   1200 = 30x
     x = 40mph, speed of car A.  Car B speed is 50mph
CHECKING our answer***
{{{120mi/40mph = 150mi/50mph }}} = 3hr
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