Answer:
15.60
Step-by-step explanation:
23.31/18=1.30 (for one gallon)
1.30*12=15.60 (for twelve gallons)
I'm fairly sure it's C - even as a prediction, if you add (4x2) and (2x2) it's 12 - and the closest is thirteen, adding on the fractions.
I hope this help and this is what you were talking about
The equation for it is...
f-1(x)=-x2-7
You just multiply both sides by -1