Question 146811
When the 2nd car reaches the intersection the 1st car is 45*25/60=18.75 miles east of it.
We have a right triangle with the hypotenuse=40
d=st d=distance s=speed, t=time
Let a=60t 
b=45t+18.75, c=40
a^2+b^2=c^2
60t^2+(45t+18.75)^2=40^2
3600t^2+2025t^2+1687.5t+351.56=1600
5625t^2+1687.5t-1248.44=0
t=.344414 hr
=21 min (approx)
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Ed
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*[invoke solve_quadratic_equation 5625, 1687.5, -1248.44]