Question

the sum of digit of a two digit number is 12 if 18 is added to it the digits are reserved find of the number​

Answer 1

let x and y be at the unit and tens place of the two digit no.

hence the digit formed will be (x + 10y)

so we are given that

x + y = 12 ............[1]

and adding 18 to the no. will reversed the digit,

so x + 10y + 18 = y + 10x

9x - 9y = 18

x - y = 2...............[2]

solving equation [1] and [2] we get

x = 7, y = 5

hence the no. is x + 10y = 7 + 10×5 = 57

Answer : 57

Answer 2

Step-by-step explanation:

★ Answer :

• The original number is 57.

★ Question :

• The sum of digit of a two digit number is 12. If 18 is added to it the digits are reserved. Find of the number.

★ To find :

• The original number.

★ Solution :

Given that the sum of both the digits is 12.

➻ Let us assume :

• Unit's digit = x
• Ten's digit = 12 - x

∴ The number = (12 - x) × 10 + x

On reversing the digits, we have x at ten's place and (12 -x) at unit's place.

∴ The new number = x × 10 + (12 - x)

➻ According to the given information,

➞ x × 10 + (12 - x) = (12 - x) × 10 + x + 18

➞ 10x + 12 - x = 120 - 10x + x + 18

➞ 9x + 12 = -9x + 138

➞ 9x + 9x = 138 - 12

➞ 18x = 126

➞ x = 126/18

➞ x = 7

➻ Therefore,

• Unit's digit = x = 7
• Ten's digit = (12 - x) = (12 - 7) = 5

Hence, the original number = 57.