Can you help please. i need answers quickly. you don't have to show working out

What’s the domain of this function? fastttt

Evaluate the expression for the given value of the variable 7a - 4a for a =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)?