Question

a number consist of two digits. the digit at tens place is twice that of the digit at the unit place. if 18 is substracted from the number, the digit is reversed. find the number​

Answer 1

$\sf\large\underline\blue{Given:-}$

•A number consists of two digits.

• The digit at ten's place is twice that of the digit at the unit place.

•If 18 is subtracted from the number, the digit is reversed.

$\sf\large\underline\blue{To\: Find :-}$

• What's the number?

$\sf\large\underline\blue{Solution:-}$

$\small{\underline{\sf{\blue{Let-}}}}$

the unit's digit of the number be x.

Given that, the digit at ten's place is twice that of the digit at the unit place.

Therefore,

Ten's digit will be = 2x

Hence,

The number will be

= 10×2x + x

= 20x + x

= 21x

Again, it’s given that

If 18 is subtracted from the number, the digit is reversed.

After reversing, the reversed number will be

= 10×x + 2x

= 12x

A.T.Q :-

⟹ 21x-18 = 12x

⟹ 21x-12x = 18

⟹ 9x = 18

⟹ x = 2

$\small{\underline{\sf{\blue{Hence -}}}}$

Unit's digit is = 2

Ten's digit is = 2×2 = 4

Therefore,

The number will be

= 21x

= 21 × 2

= 42