find the first rate of change...
(5-6)/(2-0)=(4-5)/(4-2)=(3-4)/6-4)=-1/2
So this equation has a constant velocity which means that it is linear and can be expressed as y=mx+b where m=slope=velocity and b=y-intercept, value of y when x=0...we saw earlier that the velocity or slope is -1/2 so:
y=-x/2+b, and we can use any point to solve for b, I'll use (6,3)
3=-6/3+b
3=-2+b
b=5
So the relationship if the function:
y=-x/2+5 or more neatly...
y=(10-x)/2