You should come up with the notation x that expresses the time for walking, hence the time for jogging is 7 - x.
You need to remember the formula that expresses the distance in terms of speed and time such that:
distance = speed * time
The problem provides the information that Juan walks and jogs a total of 6 miles in 7 hours such that:
`3.5x + 7(7 - x) = 6`
You need to open the brackets such that:
`3.5x +49 - 7x = 6`
`-3.5x = 6 - 49 =gt -3.5x = -43`
`x = 43/3.5 =gt x~~ 12.28 `
You may find how far he walks multiplying 12.28 by 3.5 such that:
`d_1 = 12.28*3.5 `
`d_1 = 43` miles
Hence, evaluating the time he walks yields `x ~~ 12.28 ` and how far does he walk yields `d_1 = 43` miles.