Answer:
76 comic books
Explanation:
First we must structure a formula in order to solve for the number of comic books that Michelle initially had. The formula for this problem would be:
x · \frac{1}{2}x + 18 = 56
In order to solve for x, the initial number of comic books Michelle had, you would need to subtract 18 from 56. You would then have 38. So:
x · \frac{1}{2}x = 38
Next, you'd need to get rid of the \frac{1}{2}. In order to do that, you would divide \frac{1}{2} by 38. Now, we should be left with:
x · x = 76
Now, we don't really need both x's. We can already conclude that x is equal to 76, since the following is true:
76 comic books - \frac{1}{2} (76) sold + 18 bought = 56 comic books left.
Therefore, your answer is 76 comic books.