I need help on this question

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

16. you're planning to buy a boat, a motor, and some miscellaneous boating equipment. the boat costs $325, the motor costs $225, and the equipment costs $79. if you've saved $438 toward these purchases, how much more do you need to save? a. $181 b. $281 c. $291 d. $191

Don't know how to find x given these segment lengths