Carlos drove to the train station and back. The trip there took five hours and the trip back took four hours. What was Carlos' average speed on the trip there if he averaged 68 mph on the return trip?

54.4 mph

Step-by-step explanation:

First find the distance to the train station. If it took Carlos 4 hours to come back driving at 68 mph, the distance is:

= Speed * time

= 68 * 4

= 272 miles

This means that Carlos drove for 5 hours to cover 272 miles the first time. His average speed was therefore:

= Distance / time

= 272/5

= 54.4 mph

-10i^2-4i

step-by-step explanation:

evaluate for p=2,q=5i

(2−4)(2+5i)i

(2−4)(2+5i)i

=−10i2−4i

its a straight line parallel to the time axis