To find the missing number (the percentage), we can set up the equation:
\[ \text{Percentage} \times 85 = 34 \]
Let \( x \) be the percentage expressed as a decimal (for example, if x = 0.4, that means 40%).
Now we have:
\[ x \times 85 = 34 \]
To find \( x \), divide both sides by 85:
\[ x = \frac{34}{85} \]
Now calculate \( \frac{34}{85} \):
\[ x = 0.4 \]
To convert this decimal to a percentage, multiply by 100:
\[ 0.4 \times 100 = 40 \]
Thus, the missing number is \( 40% \).
So, the answer is:
40%