En el año 2018 la poblacion mundial fue de 7576951385 y se considera que para el 2020 la poblacion mundial sera de 7797322395 de habitantes. Por tanto la poblacion mundial en 2020 sera de aproximadamente 8 billones de habitantes

I think it would be more beneficial to know how to do these then know the answers since it's quite a simple concept.

Step-by-step explanation:

You take the number outside of the parentheses(if it's just a minus sign it's a negative 1) and multiply it by the number before the plus, minus, division, or multiplication sign. You multiply it by the number after. Then do the problem from there. I'll do the first one for you. 6 times 2n equals 12n. 6 times negative 9 is -54. So your answer is 12n - 54. Hope this helps.