Data Sufficiency

On his trip from alba to benton, Julio drove the first x miles at an avg rate of 50 miles per hr and the remaining dist at an avg rate of 60miles per hr. How long did it take Julio to drive the first x miles?

1) On this trip, Julio drove for a total of 10hrs and drove a total of 530 miles.
2) On this trip, it took Julio 4 more hrs to drive the first x miles than to drive the remaining dist.

Can someone show how to solve the problem please?

x/50 = t1
(total distance-x)/60=t2
t1+t2=total time

1) t1+t2=10 and total distance = 530

so x/50=t1
(530-x)/60 = 10-t1
->
t1=(600-530+x)/60=x/50
t1=50(70+x)=60x
10x=3500
x=350
t1=350/50 = 7 hours
(180/60 = 18/6 = 3 hours, to confirm 3+7=10)
Sufficient

2) (x/50)+4 = (total-x)/60, what is the total distance? not sufficient.

Answer is A