Question

Two street cars are 11 miles apart and traveling towards each other on parallel tracks. they meet in 12 minutes. find the speed of each streetcar if one travels 15 miles per hour faster than the other

Answer 1

Let v be the speed of the slower streetcar. Then the speed of the other streetcar is (v + 15) mph.
The closing speed of the streetcars is v + v + 15 = 2v + 15.
$time=\frac{distance}{speed}$
$\frac{12}{60}=\frac{11}{2v+15}$
Cross-multiplying, we get:
24v + 180 = 660
24v = 480
v = 20
The  answer is: The speeds of the streetcars are 20 mph and 35 mph.