[tex]She \: tilled \: over \: 2 \: days: 7\frac{2}{12} + 4 \frac{11}{12} = 12 \frac{1}{2} < 15 \frac{7}{12} \\ \Rightarrow She \: didn't \: till \: enough \: soils, \: she \: need \: 15 \frac{7}{12} - 12 \frac{1}{12} = 3 \frac{1}{2} \: yards \: of \: soils \: more[/tex]
