When multiplying negative numbers, just remember 2 things. 1: 2 negative values will always give a positive value. 2: If you only have 1 negative value, your answer will also be negative. Just remember these rules and the rest is simple multiplication.
The rule of how to multiply negatives is simple: For a case where a negative number is multiplied by a positive, the rule above can be restated as: take the positive number, and the negative WITHOUT the minus sign, multiply them and add the inus sign to the product.