$7-\frac{x}{3}=12$

Step 1 ：First, isolate the term with x by adding \(\frac{x}{3}\) to both sides and subtracting 12 from both sides: \(7 - 12 = \frac{x}{3}\)

Step 2 ：Simplify the left side: \(-5 = \frac{x}{3}\)

Step 3 ：Next, multiply both sides by 3 to get rid of the fraction: \(-5 \times 3 = x\)

Step 4 ：Simplify the equation: \(-15 = x\)

Step 5 ：Final Answer: \(\boxed{-15}\)