Write 0.0004353 in scientific notation

Use set buikder notation to represent the following set: {, -2, -1, 0}

One integer is 8 times another. if the product is 72, then find the integers

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