Question 702440
D=RT
78=12T+18(5-T)
78=12T+90-18T
78-90=-6T
-12=-6T
T=-12/-6
T=2 HOURS FOR THE 12 MPH. TRIP.
5-2=3 HOURS FOR THE 18MPH TRIP.
PROOF:
78=12*2+18*3
78=24+54
78=78