Multiple choice

The ratio of the incomes of two employees is 7 : 4, and the ratio of their expenditures is 3 : 1. If each of them manages to save Rs. 4,800 per month, find the sum of their monthly incomes (in Rs.).

  1. 21,120

  2. 20,120

  3. 21,150

  4. 18,150
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let incomes be 7x and 4x, expenditures 3y and y. Savings: 7x - 3y = 4800 and 4x - y = 4800. From the second, y = 4x - 4800. Substitute into the first: 7x - 3(4x - 4800) = 4800, so 7x - 12x + 14400 = 4800, -5x = -9600, x = 1920. Total income = 11x = 11 * 1920 = 21120.

AI explanation

Let the incomes be 7x and 4x, and the expenditures be 3y and y. The savings equations are 7x minus 3y equals 4800 and 4x minus y equals 4800. From the second equation, y equals 4x minus 4800. Substituting this into the first equation gives 7x minus 3 times (4x minus 4800) equals 4800, which simplifies to 5x equals 9600. Solving for x gives 1920. The sum of their incomes is 7x plus 4x, which is 11x. Multiplying 1920 by 11 gives Rs. 21,120.

Keep practicing — related questions