Question

the sum of the digit of two digit number together with 7 is 3 times the digit in its ten's place. If 8 is subtracted from the number the digit of a number interchange their position?find the number

Answer 1

Let the number be xy.
Then according to the question we have,
10*x + y + 7 = 3*x
Simplifying this we have,
7x + y + 7 = 0....(i)

Then it says,
10*x + y - 8 = 10*y + x
Simplifying this we have,
9x - 9y = 8 ..(ii)

We have 2 equations and 2 variables, try to solve for x and y ?