What is the y intercept and slops for y=6-3x

Every time you drive you will experience a combination of driving conditions and environments.

Agreeting card company can produce a box of cards for $7.50. if the initial investment by the company was $50,000, how many boxes of cards must be produced before the average cost per box falls to $10.50?

Can someone pls ! pls answer all. no explanation needed..