Question

a number consists of two digits. The digit at the tens place is twice that of the digit at units place. If 18 is sutracted from the number, the digits are reversed. Find the number

Answer 1

Let the two digit number = 10x + y
:
"the ten's place is 2 times the digit in the unit place"
x = 2y
:
"if 18 is subtracted from the number the digits are reversed."
10x + y - 18 = 10y + x
10x - x = 10y - y + 18
9x = 9y + 18
simplify, divide by 9
x = y + 2
Replace x with 2y
2y = y + 2
2y - y = 2
y = 2
then
x = 2(2)
x = 4
:
42 is the number
:
:
Check solution in the statement:
"if 18 is subtracted from the number the digits are reversed."
42 - 18 = 24

Answer 2

Answer:

42

Step-by-step explanation:-

let the number of units place = x

Given : The digit at tens place twice of units place

Tens digit place = 2x (10) + 1 = 20x + 1 = 21x

Interchange the digits - 12x

Given : if 18 is subtracted from the number, the digits are reversed

According to the given question-

21x - 18 = 12x

21x - 12x = 18

9x = 18

x = 2.

The original number = 21 x = 21(2) = 42.

Hence :

Answer : 42