At a used book sale,5 books cost $15. How many books can u buy for $21

Noor brought 21 sheets of stickers. she gave 1/3 of a sheet to each of the 45 students at recess. she wants to give teachers 1 1/2 sheets each.

Aquadratic equation in standard from is written ax^2= bx+c, where a, b and c are real numbers and a is not zero?

When george started his current job, his employer told him that at the end of the first year, he would receive two vacation days. after each year worked, his number of vacation days will double up to five work weeks (25days) of payed vacation. how many vacation days will he have in 4 years