To determine the number of squares when there are 75 ovals, we need to know the proportionality constant or the ratio of ovals to squares. However, since that information isn't provided in your question, we cannot calculate the exact number of squares without that ratio.
For example, if the ratio of ovals to squares is 2:1, then for 75 ovals, you would have:
\[ \text{Number of squares} = \frac{75 \text{ ovals}}{2} = 37.5 \text{ squares} \]
Since the number of squares must be a whole number, if you have a specific ratio or additional information, please provide that so we can calculate the number of squares accurately. Otherwise, you will need to establish a ratio to arrive at a solution.