39-12w=7-16w need to slove step by step but how?

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

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 standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?