Factorise fully 12x-8

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?

He that is measured at 220° is a reflex angle. the opposite angle is obtuse. find the measure of obtuse .