For this case we have that if each package of pencils has 10 pencils we have:
[tex]9 * 10 = 90[/tex]
Thus, we have a total of 90 pencils.
If Peter lost 18 pencils we have:
[tex]90-18 = 72[/tex]
Thus, Peter has 72 pencils left.
Answer:
After losing 18 pencils, Peter has 72 pencils left.
Option A