Let us first find the slope, or rate of change, denoted by m in the linear equation y=mx+b
m=(y2-y1)/(x2-x1), in this case
m=(8-10)/(2-1)
m=-2/1
m=-2 (since this is a line it is constant and we don't have to check other points so see if the slope changes :P) now we have:
y=-2x+b, we can use any point now to solve for b, the y-intercept (y-intercept is the value of y when x=0), I'll use point (1,10)...
10=-2(1)+b
10=-2+b
12=b so our line is:
y=-2x+12 (note that the y-intercept, b, is the initial value)
So.
Initial Value: 12, rate of change: -2
