1/5 fraction as demicals

What is the value of the expression below? (81^2)^1/8

1) in triangle the, what is the measure of angle t (in degrees)? 2) in triangle bat, the measure of angle b is 66∘, and the measure of angle t is 77∘.what is the measure of the exterior angle at a (in degrees)?

The base of a rectangular pyramid is 13 inches long and 12 inches wide. the height of the pyramid is 8 inches. what is the volume of the pyramid