Julia bought 3 packs of red balls, 10 packs of yellow balls, and 8 packs of green balls. There were 19 balls in each package. How many balls did Julie buy in all? Give me reasons, before answering the question
The total number of packages is 3 + 10 + 8 = 21. Julia bought 21 19 = 399 balls. So the final answer is 399.