Question

The present age of Sania is 4 times her brother’s age. 5 years hence, her age will be 21 years

more than her brother’s age. Find their present ages​

Answer 1

$\large\mathfrak \pink{Solution:-}$

$\underline \mathbb{GIVEN:-}$

The present age of Sania is 4 times her brother’s age.

5 years hence, Sonia's age will be 21 years more than her brother’s age.

$\underline \mathbb{TO \: FIND:-}$

Their present aages.

$\underline \mathbb{ASSUMPTION:-}$

Let, the present age of her brother be x years

and the present age of Sania be 4x years.

After 5 years ,

The age of her brother will be (x + 5) years

and the age of Sania be (4x+5) years

$\underline \mathbb{BY \: THE \: PROBLEM:-}$

$4x + 5 = x + 5 + 21 \\ \\ \implies \: 4x + 5 = x + 26\\ \\ \implies \:4x - x = 26 - 5\\ \\ \implies \:3x = 21\\ \\ \implies \:x = \cancel\frac{21}{3} \\ \\ \implies \:x = 7$

$\underline \mathbb{ANSWER:-}$

The present age of Sania's brother = x = 7 years.

The present age of Sania = 4x = 4 × 7 = 28 years.