For this question we make a system of equations.
Moore family = let’s make them x
Hill family = let’s make them y
1325 litres of water in total. But we don’t know who used how much. So,
1325 = 20x + 25y
Also, x + y = 60 because they were running for a total of 60 hours.
Rearrange for x for both of them, let’s do x.
x= (1325/20) - (25/20)y
x= 60-y
Make them equal each other, and solve for y
(1325/20) - (5y/4) = 60 - y
Use algebra to solve for y
y = Hill, 25 hours
x = Moore, 35 hours
