he would need 14 more apples.
if you already have 11 apples and one pie would take 5, 2 pies would take 10 apples, 3 would take 15, 4 would take 20, and 5 pies would take 25 apples. 25 apples total minus the 11 he already has equals 14. he still needs 14 more apples. Hope this helps!