Answer:
Part A:
the value of the y-intercept or b (50) represents the amount of customers that were at the restaurant at 7pm because according to the problem, it says that x = 0 at 7pm. the y-intercept is (0, y)
Part B:
so you had the right idea, except instead of everything going by ones, its going by fives
every square represents 5 so the line is going down every two squares, then 5(2) = 10 and because the line is going down it would be negative
therefore, m = -10
Part C:
all you have to do now is put part a and b together
y = mx + b
m = -10 and b = 50
y = -10x + 50
or (depending on what you're doing in your class)
f(x) = -10x + 50
Part D:
at 8:30pm, you should expect 35 customers at the restaurant. this is because the (0, 50) represents the amount of customers at 7pm, so an hour an a half later would be (1.5,y) if you use the equation and plug in the 1.5 for x then it should look like this:
y = -10(1.5) + 50
y = -15 + 50
y = 35