To find the missing number in the equation \( 319 - ___ = 228 \), you can rearrange the equation to solve for the blank:
\[ __ = 319 - 228 \]
Now, calculate the right side:
\[ 319 - 228 = 91 \]
So, the missing number is \( 91 \).
Thus, \( 319 - 91 = 228 \).