Tolong yaaaaaaaa *^O^*~T_T~

Dua sudut yg membentuk garis lurus , total 180.

< CAB = 180 - 7y
< CBA = 180 - 5y

Total sudut segitiga 180

(180 - 7y) + (180 - 5y) + 3y = 180
360 - 9y = 180
360 - 180 = 9y
9y = 180
y = 180/9
y = 20 drjt (B)