Question

the tens digit of a two digit number is twice the units digit. The sum of the digits is twelve. Find the original number.

Answer 1

X - tens digit
y - units digit

$x=2y\\ x+y=12\\\\ 2y+y=12\\ 3y=12\\ y=4\\\\ x=2\cdot4\\ x=8\\\\ 10\cdot8+4=\boxed{84}$