The monthly incomes of two friends Ajay and Amit, are in the ratio 5 : 7 respectively and each of them saves Rs. 72000 every month. If the ratio of their monthly expenditure is 2 : 4, find the monthly income of Ajay(in Rs.).

Correct option is B

Given:

Monthly income ratio of Ajay and Amit = 5 : 7
Monthly savings of Ajay and Amit = ₹72000
Monthly expenditure ratio of Ajay and Amit = 2 : 4
Formula Used:
Total Income = Savings + Expenditure
Solution:
Let the monthly incomes of Ajay and Amit be ₹5x and ₹7x respectively.
Ajay's expenditure = 5x - 72000
Amit's expenditure = 7x - 72000
Expenditure ratio of Ajay and Amit is given as 2 : 4.
​$$\Rightarrow \frac{5x - 72000}{7x - 72000} = \frac{2}{4} \\\Rightarrow 4(5x - 72000) = 2(7x - 72000) \\\ \Rightarrow 20x - 288000 = 14x - 144000 \\\ \Rightarrow 20x - 14x = 288000 - 144000 \\\ \Rightarrow 6x = 144000 \\\ \Rightarrow x = 24000$$​​
Ajay's monthly income = 5x = 5 × 24000 = ₹120000