Math
posted by Anonymous .
I have been stuck on this problem for a while need help on it and soon. It's functions.
X Rule Y
10 65
30 45
50 25
70 5
I can't find the rule

Did you not notice that for every increase of 20 in the x's there is a decrease of 20 in the y's
so the slope is (4565)/(3010) = 1
so y = x + b
using x=10, y = 65
65 = 10 + b
b = 75
y = x + 75