Resposta:

triangulo 1:

x + x + x = 180

3x = 180

x = 180/3

x = 60°

triangulo 2:

x + 3 + x + 3 + 90 = 180

2x + 6 = 180 - 90

2x = 90 - 6

2x = 84

x = 84/2

x = 42°

triangulo 3:

x + 60 + 90 = 180

x + 150 = 180

x = 180 - 150

x = 30°