\(n \text{ identical objects can be placed into }r \text{ distinguishable boxes in }\\ N=\dbinom{n+r-1}{r-1} \text{ ways}\\ \text{In this problem }n=4,~r=3\\ N=\dbinom{6}{2}=15 \text{ ways}\)

\(n \text{ identical objects can be placed into }r \text{ distinguishable boxes in }\\ N=\dbinom{n+r-1}{r-1} \text{ ways}\\ \text{In this problem }n=4,~r=3\\ N=\dbinom{6}{2}=15 \text{ ways}\)