Tommy and zach are starting out at the same position. tommy runs north at 3 miles per hour and zach starts to run east 2 hours later at the rate of 4 miles per hour. how long until tommy and zach are 8 miles apart?

Y=3(t+2), x=4t

By the Pythagorean Theorem

d^2=x^2+y^2  and using y and x from the beginning and 8^2 for d^2:

64=16t^2+(3t+6)^2

64=16t^2+9t^2+36t+36

64=25t^2+36t+36

25t^2+35t-28=0  I'll just use the quadratic equation as this has no nice integer solutions :)

t=(-35±√(4025))/50  and since t>0

t≈0.5689 hr (34:07  in minutes and seconds :P )

This is the time elapsed for Zach