Multiple choice

The monthly incomes of Davinder and Malkit are in the ratio 4 : 5 and their expenses are in the ratio 5 : 6. If Davinder saves Rs. 25 per month and Malkit saves Rs. 50 per month, what are their respective incomes?

  1. Rs. 720 and Rs. 900

  2. Rs. 400 and Rs. 500

  3. Rs. 160 and Rs. 200

  4. Rs. 800 and Rs. 1000

  5. Rs. 400 and Rs. 550
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let incomes be 4x and 5x. Expenses are 5y and 6y. 4x - 5y = 25 and 5x - 6y = 50. Solving this system: multiply first by 6, second by 5: 24x - 30y = 150 and 25x - 30y = 250. Subtracting gives x = 100. Incomes are 400 and 500.

AI explanation

Let the incomes be 4x and 5x, and the expenses be 5y and 6y. Using the savings formula (Income - Expense = Saving), we get 4x - 5y = 25 and 5x - 6y = 50. Solving this simultaneous equations method yields x = 100 and y = 75. The respective incomes are 4 multiplied by 100 and 5 multiplied by 100, resulting in Rs. 400 and Rs. 500.

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