3. There are two different multiplication expressions. Each expression is made up of two integers. The product of one expression is negative and the product of the other expression is positive. How many negative integers are in BOTH expressions?
To have a negative product, one of the two integers in each expression must be positive and the other must be negative. Therefore, in both expressions, there must be one positive integer and one negative integer. Since the question asks for the number of negative integers in both expressions, the answer is $\boxed{2}$.
