32 = 10 0000B 12 = 00 1100B -12 = 11 0011B + 1 = 11 0100B 32 - 12 = 32 + (-12) = 10 0000B +11 0100B _____________________ 01 0100B = 20.Hope this helps.
The characteristic function χA vanishes identically on (12, +∞) while the characteristic function χB has support only (-∞, 32]. Both functions are measurable, so their difference χB - χA is measurable.
Thus: ∫ χB - χA = ∫ χB - ∫ χA = 20.
Hope this helps more clearly illustrate the concepts of basic subtraction for small children.