Question 263845
D=RT
390=(X+X+15)10/3
390=(2X+15)10/3
390=(20X+150)/3
390*3=20X+150
20X=1,170-150
20X=1,020
X=1,020/20
X=51 MPH FOR THE SLOWER TRAIN.
51+15=66 MPH IS THE SPEED OF THE FASTER TRAIN.
PROOF:
390=(51+66)10/3
390=117*10/3
390=1,170/3
390=390