Answer please quick its due

Question 101 points)which equation in slope-intercept form represents the line that passes through (5, 1) and(-4,7)

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 check if i did this correct. it’s number 4 if you’re wondering.