SOLUTION: Maria drove to her grandmother’s house at an average speed of 60 miles per hour. On the way home, she averaged 45 miles per hour. If she spent a total of 3 hours and 30 minutes dri

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Question 773245: Maria drove to her grandmother’s house at an average speed of 60 miles per hour. On the way home, she averaged 45 miles per hour. If she spent a total of 3 hours and 30 minutes driving, how many miles is the trip to her grandmother’s house?
Answer by pakhi(24) About Me  (Show Source):
You can put this solution on YOUR website!
Let the distance to Maria's grandmother's house be 'x' miles.
She drove to her grandmother's place at an average speed of 60miles/hr.
This means she covered 60 miles in 60 minutes.
So time she took in covering 'x' miles is (x/60)60 = x minutes
On her way home she spanned 45 miles in 60 minutes.
So time she took in covering 'x' miles is (x/45)60 = (4x)/3 minutes
So total time taken was x + (4x)/3 minutes
But total time taken was = 3 hours 30 minutes = 210 minutes
So x + (4x)/3 = 210
or (3x + 4x)/3 = 210
or 7x = 210 * 3
or x = 630/7 = 90
Therefore the distance to her grandmother's place is 90 miles.
check: Time taken in going = x minutes = 90 minutes
Time taken in coming back = (4x)/3 = 120 minutes
Total time = 90 + 120 = 210 minutes = 3 hrs 30 minutes