1 is 70 because the triangle has given angles of 45 and 65. If you add them you get 110 and a triangle is equal to 180° so 180-110 is 70.
2 is 65° because a line is equal to 180° as well so since 1 is 70 and being given 45, we add them to get 115 and 180-115 is 65.
3 is 95°because a triangle is equal to 180° so since 2 is 65 and being given 20°, you add those to get 85° and 180-85 is 95.