Question

One of the digits of a two-digit number is twice the other digit. If you interchange the
digits of this two-digit number and add the resulting number to the original number , you get 99. What is the original number?

Answer 1

Answer:

36

Step-by-step explanation:

Let the digits be x, 2x.

The original no. will be 10(x) + 2x = 12x

The new no. after interchanging will be 10(2x) + x = 21x

Adding the the 2 nos. = 99

12x + 21x = 99

33x = 99

x = 3

2x = 6

Original no. is 36.

Hope this helps! :)

Answer 2

Step-by-step explanation:

42

Let one of two digit number be x

Since we are given that One.of the two digits of a two digit number is twice the other digit

So, other digit = 2x

So, Number = 10(2x)+x10(2x)+x

Now if you interchange the digit of the two digit number

Interchanged Number = 10(x)+2x10(x)+2x

Add the resulting number to the original number you get 66

10(2x)+x+10(x)+2x =6610(2x)+x+10(x)+2x=66

20x+x+10x+2x =6620x+x+10x+2x=66

33x =6633x=66

x =\frac{66}{33}x=

33

66

x =2x=2

So, The original number = 10(2x)+x = 10(2 \times 2)+2 =4210(2x)+x=10(2×2)+2=42