bantu aku yaa teman-teman

(2x + 15) + 6x + (5x - 30) = 180
13x - 15  = 180
        13x = 180 + 15
        13x = 195
            x =  15

2x + 15 = 2(15) + 15
             = 45

5x - 30 = 5(15) - 30
            = 45

6x = 6(15)
     = 90

90 + 45 = 135°