In two inequalities below,both a and b are integers.how many values do a and b have in common?
4< a < 21 12< b < 24
-
a can be 5, 6, .. 19 or 20
b can be 13, 14, ...22 or 23.
Both a or b can be integers 13 through 20. Those are the "values in common" to both sets.