Answer:
miles left = 150 - 6d
Explanation:
To create this expression, let 150 be the total number of miles she needs to run. If she runs 6 miles every day, the expression for miles she has left is the total miles - 6* how many days she has been running. Your final expression for miles she has left should be 150 - 6d.
Hopefully this helps- let me know if you have any questions!