yg nomor 18dan19 di isi pake cara tolong besok dikumpulinn

18 ) 90 +  7x + 3x = 180
                    10 x  = 180 - 90
                         x  = 9°

19 )  78° + y° + 3y° + 2y° = 180°
                                 6y°  =  180° - 78°
                                   y°  =  17°