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Kelas 7 Matematika
Bab Perbandingan dan Aritmatika Sosial

Ayah = a
Ibu = b

a + 10 + b + 10 = 98
a + b = 98 - 20
a + b = 78

a - b = 6
a + b = 78
--------------- +
2a = 84
a = 84/2
a = 42

a - b = 6
42 - 6 = b
b = 36

Perbandingan
= 42 : 36
= 7 : 6