1. **State the problem:** We are given a rectangle with a perimeter of 60 m and one side measuring 18 m. We need to find the area of the rectangle. 2. **Recall the formula for perimeter of a rectangle:** $$P = 2(l + w)$$ where $l$ is the length and $w$ is the width. 3. **Substitute the given values:** $$60 = 2(18 + w)$$ 4. **Solve for $w$:** $$60 = 36 + 2w$$ $$60 - 36 = 2w$$ $$24 = 2w$$ $$w = \frac{24}{2} = 12$$ 5. **Calculate the area of the rectangle:** Area $A = l \times w$ $$A = 18 \times 12 = 216$$ 6. **Answer:** The area of the rectangle is $216$ square meters. Therefore, the correct option is **c. 216 m^2**.