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A red car left the park at 9 am. An hour later a blue car left the same park, heading to the same destination. If both cars arrived at the destination at 1 pm, and the speed of the blue car was 15 mph faster than the red car, what was the speed of the blue car?

Answer :

Answer: 60 mph

Step-by-step explanation:

Given

The red car left at 9 am and arrives at 1 pm

time taken by the red car [tex]t_a=4\ hr[/tex]

time taken by the blue car [tex]t_b=3\ hr[/tex]

Assume the speed of the red car is v

So, the speed of the blue car is v+15

distance traveled by them is the same

[tex]\Rightarrow v\times 4=(v+15)\times 3\\\Rightarrow 4v=3v+45\\\Rightarrow v=45\ mph[/tex]

Thus, the speed of the blue car is [tex]45+15=60\ mph[/tex]