One set of barrettes costs $3 each, and one comb costs $1 each. Kristine buys one set of barrettes and one comb. Crystal buys three sets of barrettes and one comb. How much do the two girls spend altogether?
Kristine spends $3 + $1 = $<T>add(3, 1)=4
Three sets of barrettes cost 3 x $3 = $<T>multiply(3, 3)=9
Crystal spends $9 + $1 = $<T>add(9, 1)=10
Therefore, the two girls spend $4 + $10 = $<T>add(4, 10)=14
