Let m = the number of pencils Michelle has.
So, Leslie has m - 9 = 8.
Add 9 to both sides:
m = 17. So Michelle has 17 pencils, and Leslie has 8, which is 9 fewer than 17
So, Leslie has m - 9 = 8.
Add 9 to both sides:
m = 17. So Michelle has 17 pencils, and Leslie has 8, which is 9 fewer than 17