Question 499760
d = rt is the basic distance equation.
d = 185
.
t = 3 hr 30 min = 3.5 hr
.
x = time spent driving at 50
(3.5-x) = time spent driving at 55
.
So,
50x + 55(3.5-x) = 185
.
50x + 192.5 - 55x = 185
.
-5x = -7.5
.
x = 1.5 hr driving at 50
.
3.5-x = 3.5 - 1.5 = 2 hr driving at 55
.
Done.