Can someone help me understand this math problem?

Select the correct answer from the drop-down menu. subtracting 3xy^2 from 8xy^2 gives the same result as the expression. [tex]3xy ^{2} - 8xy ^{2} [/tex][tex] { - 7xy}^{2} - {2xy}^{2} [/tex][tex] {7xy}^{2} - {2xy}^{2} [/tex]

Which function represents the sequence? f(n)=n+3 f(n)=7n−4 f(n)=3n+7 f(n)=n+7

The plant were you work has a cylindrical oil tank that is 2.5 feet across on the inside and 10 feet high. the depth of the oil in the tank is 2 feet. about how many gallons of oil are in the tank?