Jules can make m muffins in s minutes
so, Jules making rate is [tex] \frac{m}{s} [/tex]
Alice can make n muffins in t minutes
so, Alice making rate is [tex] \frac{n}{t} [/tex]
now, we can find total rate when they make together
total rate is
[tex] =\frac{m}{s}+\frac{n}{t} [/tex]
now, we can combine it
[tex] =\frac{mt+ns}{st} [/tex]
now, we can find total number of muffins in 30 minutes
[tex] =30*(\frac{mt+ns}{st}) [/tex]
so, option-C......Answer