Question 908176
Gaining speed 8.5 -4= 4.5 mph
Headstart 4*0.5 =2 miles
Time to catch up 2/4.5=0.44444444 hours
Time to catch up =26.6666667 minutes
Algebraic solution
4(t+0.5)=8.5t
4t+2.0=8.5t
2.0=8.5t-4t
2.0=4.5t
t=0.44444444  hours