1. **Problem Statement:** Quadrilateral MNOP is dilated by a scale factor of $\frac{3}{4}$ to form quadrilateral M'N'O'P'. We need to find the length of side O'P'. 2. **Given:** Side OP = 28.3 units, scale factor $k = \frac{3}{4}$. 3. **Formula:** When a figure is dilated by a scale factor $k$, each side length of the image is $k$ times the corresponding side length of the original figure. 4. **Calculation:** $$ O'P' = k \times OP = \frac{3}{4} \times 28.3 $$ 5. **Simplify:** $$ O'P' = \frac{3}{4} \times 28.3 = \frac{3 \times 28.3}{4} = \frac{84.9}{4} $$ 6. **Divide:** $$ O'P' = 21.225 $$ 7. **Answer:** The length of side O'P' is $21.225$ units. This means the side O'P' is smaller than OP by the scale factor $\frac{3}{4}$, which is consistent with the dilation reducing the size of the figure.