Jawabanmu

2014-05-23T11:50:26+07:00
ABC=ADC 
5x + 10 = 4x + 30
5x - 4x = 30 - 10
x = 20

ABC = 5X20 + 10
        = 100 + 10 = 110
ADC = 4X20 + 30
        = 80 + 30
       = 110
BCD = 60 

LUAS BAD = 360 - ( 110+110+60)
                 = 360 - 280 
= 80 DERAJAT