Function or non function !!

Landon wrote that 3−2.6=4. which statement about his answer is true?

At your job you're paid $50 per week plus $3 per sale at least how many saled do you need to make in order to have over $250

Mallory has been offers two different jobs. she can baby sit for 6 hours a week and get $8.50 an hour. or she can work at the library for 14 hours a week and make $5.50 an hour. which job will allow her to save the most money after 6weeks?