Jules can make m muffins in s minutes. Alice can make n muffins in t minutes. Which of the following gives the number of muffins that Jules and Alice can make together in 30 minutes?
A$\frac{m+n}{30st}$
B$\frac{30(m+n)}{st}$
C$30 \left( mt + ns \right)$
D$\frac{30(mt + ns)}{st}$正確答案
答案與詳解
