So, each serving requires:
3 1/4 divided into 13:
[tex] 3\frac{1}{4} /13= \frac{13}{4} * \frac{1}{13} = \frac{1}{4} [/tex]
let's check from the second information:
4 2/4 divided into 18:
[tex] 4\frac{2}{4} /18= \frac{18}{4} * \frac{1}{18} = \frac{1}{4} [/tex]
so for 28, we need:
[tex] \frac{1}{4} *28= \frac{28}{4} = \frac{14}{2} = 7[/tex]
we need 7 cups of flour!
