Question #538e8

1 Answer
Apr 28, 2017

T = 20w + 10(20-w) or T = 10w +200

Explanation:

We can figure out that when John walks, it takes him 20 minutes to complete one mile. Therefore, you can start your equation with T = 20w, which will tell you how long John spends walking.

To figure out how long John spends running, you then need to find out how many miles he runs by subtracting w, the miles he does not run, from 20, the total miles. Because we don't know what w is, we can leave this as an expression. Finally because we can figure out that it takes John 10 minutes to run a mile, so we can multiply 10*(20-w) and add this on to our equation, giving us T = 20w + 10(20-w), or when simplified, T = 10w +200

Another way to solve this equation would be to calculate how long it would take for John to run the entire course by doing 20 miles times 10 mph to get 200. Then, because it takes him 10 minutes longer to walk one mile than to run it, you can simply add 10 minutes for every mile that he walks, leading you to the same final equation of T = 10w +200.