Shari drove for 90 miles in the city. When she got on the highway, she increased her speed by 20 mph and drove for 130 miles. If Shari drove a total of 4 hours, how fast did she drive in the city?
1 Answer
Dec 11, 2016
45 mph
Explanation:
Let's call her speed in the city
Speed is miles per hour -speed=
Rearranged
Time =
So in the city the time is
After the time is
The total time is 4 hours
So
The common denominator is
So
Divide through by 4
Factorise
So
Check it out 90 miles at 45mph plus 130 miles at 65 mph is 4 hours