Please I need help ASAP

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

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

Which function is odd check all that apply a. y=sin x b. y=csc x c. y=cot x d. y=sec x