To determine the correct first step, we need to analyze the problem Ryan is attempting to solve:
He is multiplying \( 5 \cdot (-2) \cdot \left(\frac{1}{2}\right) \).
In order to arrive at the second step ("Multiply 5 by -1"), Ryan likely first simplified the multiplication of \( (-2) \cdot \left(\frac{1}{2}\right) \).
Since this multiplication involves \( -2 \) and \( \frac{1}{2} \), the appropriate first step should be:
Multiply -2 by \(\frac{1}{2}\).
This would yield \( -1 \), and then the next step would indeed involve multiplying \( 5 \) by \( -1 \).
So, the correct answer that fills in the blank is:
Multiply -2 by \(\frac{1}{2}\).