<PRE><B>Question 214899</B>
Pete drove from Buffalo to Boston, a distance of 720km. On return trip he increased his speed by 10km/h. If the total trip took 17h, what was his speed from Boston to Buffalo? 
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(720/r) + 720/(r+10) = 17
720r + 720(r+10) = 17r*(r+10)
1440r + 7200 = 17r^2 + 170r
17r^2 - 1270r - 7200 = 0
*[invoke solve_quadratic_equation 17,-1270,-7200]
r = 80 km/hr Boston to Buffalo
r = 90 km/hr return
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