tolong sama caranya ya mksh :))

1.Misal : Ibu :a
Anak :b
[tex]a = 3b \\ a - b = 30 \\ \\ substitusi \\ a - b = 30 \\ 3b - b = 30 \\ 2b = 3 \\ b = 15 \\ \\ a = 3b \\ a = 3(15) \\ a = 45[/tex]
2.