Question

The average rate of the first part of Yi’s walk on a park loop was 4 miles per hour. She then met up with a friend and the two walked the rest of the way at an average rate of 5 miles per hour. The entire 3-mile walk took Yi 42 minutes (0.7 hour). Which equation can be used to solve for x, the time in hours that Yi spent walking before meeting her friend?

Answer 1

So she walked during this time with 4 miles per hour (x*4)

during the rest of the way (which is 0.7-x, as the whole way took her 42 minutes, so the rest is 0.7-x) she walked with 5 miles per hour - the distance was (0..7-x)*5 m/h



the total distance was 3 miles, so if we sum the two distances, we will get 3 miles:

x*4+ (0.7-x)*5=3

let's remove the bracket:

4x+0.7*5-5x=3

4x+3.5-5x=3

subtract 3.5 from both sides:
4x-5x=3-3.5
-x=-0.5
 
multiply both sides by  (-1)
x=0.5:

so she walked for half an hour alone, that is for 30 minutes!

Answer 2

Answer:

D, 4x + 5(0.7 – x) = 3.

Step-by-step explanation:

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