A line passes through the point (-8,9) and has a slope of - 3 over 4 write an equation in slope intercept form for this line

In the diagram below, dab and dac are adjacent angles. if mdac = 25°, what is mdab in degrees? what is mbac in degrees?

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?

How do you use the elimination method for this question? explain, because i really want to understand!