Question

In a 2-digit number, the number in the unit's place is 4 more than the number in the ten's place. If the digits of the number are reversed, the new number is 6 more than thrice original number. Find the original number.

Answer 1

x - tens digit
y - units digit


`y=x+4\\ 10y+x=3(10x+y)+6\\\\ 10(x+4)+x=3(10x+x+4)+6\\ 10x+40+x=30x+3x+12+6\\ -22x=-22\\ x=1\\\\ y=1+4\\ y=5\\\\ 10\cdot1+5=\boxed{15}`