I suppose you're supposed to convert 100111 from base 2 to base 10. We have

so the missing number is 39.
To find the missing value of the equation 3-X=11 first move all the terms that have X to the right side of the equation. So -X=8( Since 11-3=8). Then divide both sides of the equation by -1 to get rid of the negative on the X. Your answer is X=-8.