Algebraically half of the sum of a number and 12 could be written as what?

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

[15 points]find the quotient with the restrictions. (x^2 - 2x - 3) (x^2 + 4x + 3) ÷ (x^2 + 2x - 8) (x^2 + 6x + 8)

Helena lost her marbles. but then she found them and put them in 44 bags with mm marbles in each bag. she had 33 marbles left over that didn't fit in the bags.