The monthly incomes of two friends Mohan and David, are in the ratio 5 : 8, respectively, and each of them saves ₹75,000 every month.

Let the monthly incomes of Mohan and David be $5x$ and $8x$ respectively.

Let their monthly expenditures be $E_M$ and $E_D$.

We are given:

• Each saves ₹75,000 → Income − Expenditure = Savings

$5x - E_M = 75000 \quad ...(1)$
$8x - E_D = 75000 \quad ...(2)$

• Ratio of expenditures = 1 : 4 → $E_M : E_D = 1 : 4$ → $E_D = 4 E_M$

Step 1: Substitute $E_D = 4 E_M$ in (2)

$8x - 4E_M = 75000$

From (1): $E_M = 5x - 75000$

Substitute into above:

$8x - 4(5x - 75000) = 75000$

$8x - 20x + 300000 = 75000$

$-12x + 300000 = 75000$

$-12x = -225000$

$x = 18750$

Step 2: Mohan’s monthly income

$5x = 5 \cdot 18750 = 93750$

Answer: ₹93,750