Answer:
The container can hold 15 gallons of water
Explanation:
Step 1
Determine the proportion of water initially in the container;
initial amount=7/10×x=0.7 x
Step 2
Determine the remainder proportion of the water after pouring 3 gallons using the expression below;
remainder proportion=initial proportion-proportion poured
where;
remainder proportion=1/2 x=0.5 x
initial proportion=0.7 x
proportion poured=unknown=p
replacing;
0.5 x=0.7 x-p
p=0.7 x-0.5 x
p=0.2 x
proportion poured=0.2 x
But;
0.2 x=3 gallons
x=3/0.2=15 gallons
x= 15 gallons
The container can hold 15 gallons of water