Answer:
8 from the box on right corner
12500 cause 5000 goes into 12500 twice and it would be 24$ for 10000 sqft and then another 6 so 30$ cause 2500 is half of 5000
-1 would be your answer. f(0) = -4. f(1) = f(0)+3 so f(1) = -1
I am assuming you want to solve for m in each case
8n = -3m + 1
8(-2) = -3m + 1
-16 = -3m + 1
-3m = -17
m = 
8(2) = -3m + 1
16 = -3m + 1
-3m = 15
m = -5
8(4) = -3m + 1
32 = -3m + 1
-3m = 31
m = 
X=3, y=4
x=-2, y=9
Set x equal to anything, then isolate y to get the other number.