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

Ex.

(4 x 4) + (4 x 2) = 24
   16    +     8

So, how did I know how to add these two? Well, using PEMDAS (Parenthesis, Exponent, Multiplication, Division, Addition, Subtraction) we know whatever's in the parenthesis is what we do first. Since we have to sets of multiplication problems in parenthesis, we can solve either one first, but still regarding the rule of PEMDAS. Make notice of the + sign (bold) in between the two parenthesis. This tell me I will add the two products and get my final answer. But let's say it were the be subtraction oppose to addition.

Ex.

(4 x 4) - (4 x 2) = 8
   16    -    8

Using PEMDAS, I did the parenthesis first. I knew to subtract because of the - sign in the equation, leading to my difference.