SOLUTION: Deborah drove 5 hours on a secondary roads at a steady speed. She completed her trip by driving 3 hours on an interstate highway. Her total trip was 445 miles. Her speed on the int

Question 1015510: Deborah drove 5 hours on a secondary roads at a steady speed. She completed her trip by driving 3 hours on an interstate highway. Her total trip was 445 miles. Her speed on the interstate highway portion of the trip was 15 miles per hour faster than her speed on the secondary roads. How fast did she travel on the secondary roads?
Answer by josgarithmetic(39618) (Show Source): You can put this solution on YOUR website!
RT=D relates rate, time, distance. Study this table of data, and decide how to supply the missing
information.

                     rate         time     distance
secondary roads       r            5
interstate hwy        r+15         3
Total                                        445

This is how to do that:

                     rate         time     distance
secondary roads       r            5       r*5
interstate hwy        r+15         3       (r+15)*3
Total                                        445

Distance sum is the equation in one variable only, r,
.

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