X+12*3=81

To solve the equation \( X + 12 \cdot 3 = 81 \), start by performing the multiplication:

\[ 12 \cdot 3 = 36 \]

Now, substitute that back into the equation:

\[ X + 36 = 81 \]

Next, isolate \( X \) by subtracting 36 from both sides:

\[ X = 81 - 36 \]

Now, calculate the right side:

\[ X = 45 \]

So, the solution is:

\[ X = 45 \]