The distributive property of multiplication simply means multiplying the outside number to each of the numbers inside the parenthesis.
In our expression, 5 (2z + 4), our outside number is 5. We are going to multiply 5 by each of the numbers inside the parenthesis.
Here:
5 x 2z = 10z
5 x 4 = 20.
Therefore, 5(2z + 4) = 10z + 20. Option B.
