she waters her plants with 25 1/2 gallons
with the new system, she does it with 19 3/4, what's the difference/savings?
[tex]\bf \begin{cases}
25\frac{1}{2}\implies \cfrac{25\cdot 2+1}{2}\implies \cfrac{51}{2}
\\\\\\
19\frac{3}{4}\implies \cfrac{19\cdot 4+3}{4}\implies \cfrac{79}{4}
\end{cases}
\\\\\\
\cfrac{51}{2}-\cfrac{79}{4}\implies \cfrac{102-79}{4}\implies \cfrac{23}{4}\ gallons\ per\ day\impliedby \textit{LCD of 4}
\\\\\\
\textit{now, how much will it be for 30days?}\qquad 30\cdot \cfrac{23}{4}\implies \cfrac{15\cdot 23}{2}
\\\\\\
\cfrac{345}{2}\implies 172\frac{1}{2}\textit{ gallons}[/tex]
