# Math Help - Solve for variable using d=rt ?

1. ## Solve for variable using d=rt ?

1) You drove from your home to Dallas at an average speed of 60mph, and returned hom at an average speed of 45 mph. If the total driving time was 21 hours, how far is it from your home to Dallas?

2) If 5r=9t+7, what is the value of t? (remember to use distance = rate x time or d=rt)

AND NO, 1 AND 2 ARE NOT RELATED QUESTIONS.

2. Originally Posted by cherubee
1) You drove from your home to Dallas at an average speed of 60mph, and returned hom at an average speed of 45 mph. If the total driving time was 21 hours, how far is it from your home to Dallas?
Let x = time taken to go to Dallas
y = time for return journey

total time

x + y = 21 .............................(1)

Now, Distance = rate . time

so, 45y = 60x

so, $y = \frac{4}{3}x$............................(2)

solve eqn (1) and (2) to find x, and then find distance, which is 60x. finish up.