Question

20.
The age of Pravin is 6 years less than thrice the age of his younger brother.
Pravin is 21 years old, how old is his younger brother?
a) 9 years
b) 5 years
c) 13 years
d) 15 years
​

Answer 1

5year because less than Pravin

Answer 2

Answer:-

Option a) 9 years is correct.

Step-by-step explanation:-

To Find:-

• The age of his younger brother ...(?)

Given that,

• Age of Pravin is 21 years.
• The age of Pravin is 6 years less than thrice the age of his younger brother.

Solution:-

Let the age of Pravin's younger brother be x years and let the age of Pravin be 3x - 6 years.

Let's first make an equation,

: ⟹ 3x - 6 = 21

Transposing 6 to R.H.S

: ⟹ 3x = 21 + 6

: ⟹ 3x = 27

: ⟹ x = 27/3

: ⟹ x = 9

So, the age of Pravin's younger brother is 9 as we has assumed his brother's age as x

Now, Verification

⟹ 3x - 6 = 21

We got ( x = 9 ), By putting the values,

⟹ ( 3 × 9 ) - 6 = 21

⟹ 27 - 6 = 21

⟹ 21 = 21

L.H.S = R.H.S

Hence, Proved.

Required Answer

Option a) 9 years is correct.

The age of Pravin's younger brother is 9 years.