Question 748267
D=RT
D+10=8T OR 
D=8T-10 FOR THE 10 MPH BIKER.
D=6T FOR THE 5 MPH BIKER.
SET THE DISTANCE EQUATIONS EQUAL & SOLVE FOR T.
6T=8T-10
6T-8T=-10
-2T=-10
T=-10/-2
T=5 HOURS ANS.