Question 60997
300=rt or r=300/t
300=(r+10)(t-1.5) now substitute (300/t) for r in the second equation we get
300=(300/t+10)(t-1.5)
300=(300/t*t)+10*t+(300/t*-1.5)+(10*-1.5)
300=300+10t-450/t-15
0=10t-450/t-15
0=(10t^2-450-15t)/t
0=10t^2-15t-450
(5t+30)(2t-15)=0
5t+30=0
5t=-30
t=-30/5
t=-6
2t-15=0
2t=15
t=15/2
t=7.5 hours then
300=r*7.5
r=300/7.5
r=40 mph speed of trip