How do you find the sides of a triangle when you know the angles

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

Divide. reduce the answer to lowest terms.5 2/3 ÷ 3 1/9

Tickets to a science exposition cost $5.75 each for studentd and $7.00 for adults.how many students and adults went if the ticket charge was $42.75