Question 180564
Steve traveled 150 miles at a certain speed. Had he gone 20mph faster, the trip would have taken 2 hours less. Find the speed of his vehicle.
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t = 150/r  t=time, r=rate
t-2 = 150/(r+20)
Sub for t in 2nd eqn
(150/r)-2 = 150/(r+20)
Multiply by (r+20)
(150(r+20)/r)-2(r+20) = 150
Multiply by r
150(r+20) - 2r(r+20) = 150r
{{{150r + 3000 - 2r^2 - 40r = 150r}}}
{{{2r^2 + 40r - 3000 = 0}}}
{{{r^2 + 20r - 1500 = 0}}}
(r+50)*(r-30) = 0
r = 30, r = -50 *********(Ignore the -50)
r = 30 mph