Let the income of A, B and C be A, B and C respectively. Given 5% of A = 15% of B ⇒ A : B = 3 : 1 Also 10% of B = 20% of C ⇒ B : C = 2 : 1 ⇒ A : B : C = 6 : 2 : 1 C=
1
6+2+1
of (total income of A, B and C) Hence the total income of A, B and C = 9 × C= 9 × 20 thousand = `180 thousand.