What is another way to name 28 ten thousands

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

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?

Asporting good store is offering 30 percent off of the original price(x) of football cleats. the discount will be reduced by an another $7 before sales tax.