In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
walk for hunger:
donations = $85.50
mile ==> $5.25
total amount = $216.75
Step 02:
total miles:
total amount = donations + #miles * rate ( $ per mile)
216.75 = 85.50 + #miles * 5.25
216.75 - 85.50 = #miles * 5.25
131.25 / 5.25 = #miles
25 = #miles
The answer is:
He walked 25 miles