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?

A table showing Rate in mile per hour, Time in hours, and Distance in miles. The first row shows Part 1 and has 4, x, and 4 x. The second row shows Part 2, and has, 5, 0.7 minus x, and 5 left-parenthesis 0.7 minus x right-parenthesis.

x = 0.7 – x
x + (0.7 – x) = 1
4x + 5(0.7 – x) = 1
4x + 5(0.7 – x) = 3

The equation can be used to solve for x, the time in hours that Yi spent walking before meeting her friend would be D; 4x + 5(0.7 – x) = 3.

What is a system of equations?

A system of equations is two or more equations that can be solved to get a unique solution. the power of the equation must be in one degree.

Total distance covered = 3 miles.

The first part walked at the rate of 4 miles per hour.

Let us consider x hours was walked in the first part.

Total distance covered in x hours at the rate of 4 miles per hour will be 4x.

Now, the Second walk rate with meeting with friend will be 5 miles per hour.

The Total time is taken = 0.7 hours.

Therefore, time is taken in the second walk only = (0.7 - x) hours.

Distance covered in second walk = 5 (0.7 - x).

Total distance covered = distance covered in the first part + distance covered in the second part.

4x + 5 (0.7 - x) = 3 miles.

Hence, correct option is D; 4x + 5(0.7 – x) = 3.

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