Let us initially distribute 2 apples to each children.
So, the remaining 15 apples are to be distributed such that each children can get any number of apples.
So, the required number of ways will be given by N=Cr−1n+r−1.
⇒N=C215+3−1
⇒N=C217
⇒N=217×16
⇒N=136