Pls answer this and explain!

Well if you add up all 3 angles in a triangle you’d get 180 degrees as the answer.

So we can. Jus substitute.

For number 19 you can do this

57+x+x+87+50=180

Now combine like terms

194+2x=180

Now solve

x=-7

Now we can subsitute that into angle A

57+ (-7) which is 50

Measure of angle A is 50.

For number 19 it’s the same thing.

9x+14+16x-4+80=180

Now combine like terms

25x+90=180

Solve

25x= 90

x= 3.6

Now subsitue for A

3.6*9+4 which is 36.4

A is 36.4

hi friend

here is your answer

there are two angles that are alternate interior angle with angle 9

the angle 15 and angle 7 are alternate interior angle with angle 9.

hope it is for you so mark my answer as a brainliest