10 less than a number k equals 5. write the word sentence as an equation

Ineed with number 17 i don’t get it at alll

Achemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?

Areal estate agent earns $32,000 a year plus $1,000 for each apartment he sells. write an equation that shows the relationship between the number of apartments abe sells, n, and the total amount he earns in a year, e. what is the total amount abe would earn from selling 10 apartments in one year