so the groups of angles that make a line (like 130 and i or p a and t) should equal 180. however, the triangles should also equal 180. so in this case for the top row, we know that 130+j=180. since 180-130=50 (i did the inverse of addition, subtraction), j=50. now let’s say for that triangle that your top two angle measures were the 50 we just found and the 70 you have written just as an assumption but i have no clue what you were actually given. since triangles angles must equal 180, 50+70+that angle =180. 50+70=120, so if we do the inverse of 180-120=60, we find out that the bottom angle is 60 degrees.