Question 387213
Let X be the tens digit
Let Y be the units digit

The value of the two digit number is calculated as 10*X + Y, since X is the digit in the tens spot. Since this number is 11 times its units digit, then

10*X + Y = 11*Y
Subtract Y from both sides:
10*X + Y - Y = 11*Y - Y
10*X = 10*Y
Divide both sides by 10:
{{{(10*X)/10 = (10*Y)/10}}}
X = Y
(Which makes sense if you think about two-digit multiples of 11.)

The sum of the digits is 12, so:
X + Y = 12

Substitute the value of X from the first equation:
Y + Y = 12
2*Y = 12
Divide both sides by 2:

{{{(2*Y)/2 = 12/2}}}
Y = 6
Substitute in the first equation for X:
X = 6
So, the two-digit number is 66