Question

I need an expression for this scenario: Joe and Louise are making a drive from San Diego to Salt Lake City. After four hours of driving they are 507 miles from Salt Lake City. Eight hours into their trip they are only 267 miles away from their destination. Assume they averaged the same speed for the entire trip.

Answer 1

Let d be the distance from San Diego to Salt Lake City and let r be the average speed for the trip.
rate * time = distance.
{d - 4 r = 507, d - 8 r = 267}
Solve the above for d and r.
{d = 747 miles, r = 60 mph}