Question

what is the anwser to
7(4z+8b)

Answer 1

do 7x4= 28 then add z 
7x8= 56 then add b 
so your answer is 28z + 56b

Answer 2

7(4z+8b) = 28z + 56b
Times 7 by 4z to get 28z
Times 8b by 7 to get 56b
z and b are different so you can't mix them. e.g. zebra's and bears. Therefore, the answer is 28z + 56b.