Answer:
[tex]172\frac{1}{2}[/tex] gallons
Step-by-step explanation:
Considering she waters her plants with 25 1/2 gallons i.e 51/2
and with the new system, she does it with 19 3/4 i.e 79/4
taking the difference:
[tex]\frac{51}{2} - \frac{70}{4}[/tex] = [tex]\frac{23}{4}[/tex] gallons per day
For 30 days:
30 x [tex]\frac{23}{4}[/tex] = 172.5 or [tex]172\frac{1}{2}[/tex] gallons