Answer:
Step-by-step explanation:
step 1
Find the volume of the tank
step 2
we know that
If the tank is 1/3 full of water
then
the volume of water required to completely fill the tank is equal to 2/3 of the tank capacity
so
$21
21+42=63
x=63:3
x=$21
B its B
I do not konw. SOREY