Solve and check the equation. \[ \frac{7 x}{5}-3=18 \] Belect the correct choice below and, if necessary, fill in the answer box to complete your answer. A. The solution set is \{\} . (Type an integer or a simplified fraction.) B. The solution set is $\{x \mid x$ is a real number $\}$. C. The solution set is $\varnothing$.

Step 1 ：The given equation is a linear equation in one variable. To solve for x, we need to isolate x on one side of the equation. We can do this by first adding 3 to both sides of the equation to get rid of the -3 on the left side. Then, we can multiply both sides of the equation by 5/7 to solve for x.

Step 2 ：The solution to the equation is x = 15. This means that if we substitute x = 15 into the original equation, the equation should hold true.

Step 3 ：Final Answer: The solution set is \(\boxed{\{15\}}\).