For this case we must do a subtraction, for this we convert the mixed numbers given in fractions:
[tex]2 \frac {1} {5} = \frac {10 + 1} {5} = \frac {11} {5}\\1 \frac {3} {8} = \frac {8 + 3} {8} = \frac {11} {8}[/tex]
We subtract to know what fraction of mass of corn needs Miss Smith.
[tex]\frac {11} {5} - \frac {11} {8} = \frac {8 * 11-5 * 11} {40} = \frac {88-55} {40} = \frac {33} { 40}[/tex]
Thus, it lacks[tex]\frac {33} {40}[/tex] of pounds of corn dough.
Answer:
[tex]\frac {33} {40}[/tex]
