Answer:
a) 15
b) y = 15x + 325 (slope intercept), 15x - y = -325 (standard), y - 400 = 15(x - 5) (point-slope)
c) f(x) = 15x + 325
d) $505
Explanation:
a) Find the slope by taking the change in y between any two points and divide it by the change in x between those same two points. I chose (0, 325) and (5, 400). That's 75/5, which is 15.
b) Slope intercept form (y = mx + b) can be gotten from plugging in your known slope (15) and y intercept, where y = 0, which is a point given, so it's 325, giving you an equation of y = 15x + 325. Point-slope (y - y1 = m(x - x1)) can be gotten by just getting rid of the b term from the last one and plugging in the x and y values for any point. I chose (5, 400) for an equation of y - 400 = 15(x-5). Standard form (ax + bx = c) can be gotten by taken the slope intercept equation and subtracting 15x from both sides. A needs to be positive (and whole, but that's covered already), so you multiply everything by -1 to get 15x - y = -325.
c) Function notation just means replacing y with f(x) on any of the equations just obtained. I picked slope intercept (arbitrary) to get f(x) = 15x + 325.
d) This is asking you to plug in 12 to any of your equations and see what the output is. Again, I chose the slope intercept equation because it's easiest for me, but any of them will get you the exact same answer.
15(12) + 325 = 180 + 325 = 505. Don't forget your units (:
Let me know if you need anything else with this!