Question 302973
D=RT
45=RT SMITH'S TRIP
T=45/R
70=(R+5)(T+.5) JONES' TRIP
70=(R+5)(45/R+.5)
70=(R+5)(45+.5R)/R
70=(45R+2.5R+225+.5R^2)/R
70R=.5R^2+47.5R+225
.5R^2+47.5R-70R+225=0
.5R^2-22.5R+225=0
(.5R-15)(X-15)=0
.5R-15=0
.5R=15
R=15/.5
R=30 MPH. FOR SMITH'S SPEED.
45=30*T
T=45/30=1.5 HOURS.
JONES' SPEED=30+5=35 MPH.
70=(35)(1.5+.5)
70=35*2
70=70