Explain how you know whether to add or subtract when you use the distributive property to multiply

Well, when you're using the distributive property you'll know when to add or subtract when you multiply if the big number is negative and the small number is negative whatever the product is will be positive. If the big number is negative and the small number is positive the product will be negative. If the big number is positive and the small number is negative the product will be positive. And of course you should already know if they are both positive then keep it positive.