Question

how many two digit numbers are there which are more trebled their digits reversed​

Answer 1

Let x denote the digit in the tenth place and y denote the digit in unit place.. So, the number may be written as x y 10 + in the expanded form. (just like 35= 10(3) +5)

When the digits are reversed, x becomes the digit in unit place and y becomes the digit in the tenth place. The changed number, in the expanded form is 10y+x.

According to the first condition, we have y=2x which is written as

2x−y=0 (1)

Also, by second condition, we have

(10+x)−(10x+y)=27

That is, −9x+9y=27→−x+y=3 (2)

Adding equations (1) and (2), we get x= 3.

Substituting x 3 = in the equation (2), we get y = 6.

Thus, the given number is (3×10)+6=36.