Please help me solve #9, and please 10

Answer:
#9. y = -250x
#10. y = -2500, x = 100
Step-by-step explanation:
y = mx +b
y: y-value
m: slope
x: x-value
b: y-intercept
since your answer for #8 is -250, the slope would be -250 or m would be -250
y = -250x+b
now to solve for b, we take one of the points and plug it in, any works, but we'll use (1,-250)
plug in the points
-250 = -250(1)+b
solve for b
b = 0
thus the equation is y = -250x + 0 or y = -250x
#10 plug in x values and y values into equation to get answer
x = 10 -> y = -250(10) = -2500
y = -25,000 -> -25,000 = -250x
x = -25,000/-250
x = 100