tolong rumus ny no 4 y.terima kasih

Sudut berpenyiku total 90 drjt
6x + 3x = 90
9x = 90
x = 90/9 = 10

Sudut B = 3x
= 3(10)
= 30 derajat (c)

A+B=90
6x+3x=90
9x=90
x=10°

<B = 3.10 =30°