Question

A father gives 1% of his monthly income to his 2 sons as a pocket money. The elder son gets 80% of the total amount of money given and he spends 80% of his shares. If he saves rupees 20 per month, determine father's monthly income.

Answer 1

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Let father's monthly income be x .

Now

Amount is given To his Sons

= 1 % of his salary = x × 1/100 = x/100

again, Amount is Received by elder Son = 80% of x/100 = 80/100 × x/100

= 80x/10000 = 8x/1000 = x/125

it is given that he spends 80% of his share

So Amount saved by elder son = 20%

so, amount saved by elder son = 20% of amount gained by elder son

= 20 /100 × x/125

= x/625

a/c to question, amount saved by elder son =20 rs.

or, x/625 = 20

or, x = Rs 12,500