Question

A number consists of two digits. the digits at the units place is 3 times the digit at the tens place. If 36 is added to the number, the digits are reversed. Find the number?

Answer 1

The number is 26.

Explanation:

Let the number be xy.

Then:

y = 3x also:

10x + y + 36 = 10y + x

9x - 9y = = -36

x - y = -4

Substituting y = 3x in the above equation:

x - 3x = -4

-2x = -4

x = 2.

and y = 3*2 = 6.

Answer 2

x = that number

x = 10a + 3a =13a

x_reverse = 3ax10+a =31a

Have:

13a+36 =31a

=> a =2

=> x =26