Need help trying to solve​

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

Ivan and jeff buy a package of 8 pens for $4.00. ivan wants 5 of the pens, and jeff wants 3.how much should each student pay?

The area of a rectangle is 54x^9y^8 square yards.if the length of the rectangle is 6x^3y^4 yards,which expression represents the width of the rectangle in yards