bantuin nomer 19 sama 20 dong...

19. a) 1 = 3 , 4 =1
       b) 1=2, 4=3

 20. (2x + 5) + (3x + 10) = 180 derajat
=5x + 15 = 180
=5x = 165
= x = 33

sudut BOC = 2x + 5
= 33 x 2 + 5
= 71 derajat