we have that
2005 ------> 12,096 people were afflicted -----> ordered pair (0,12,096)
2006 -----> 12,096-203=11,893 people ----> ordered pair (1,11,893)
Find out the linear equation
step 1
Find out the slope
m=(11,893-12,096)/(1-0)
m=-203/1
m=-203 people per year ---> is negative because is a decreasing function
step 2
Find out the linear equation in slope-intercept form
y=mt+b
where
m=-203
b=12,096 (initial value)
therefore
The linear equation is
y=-203t+12,096
The slope is -203 people per year
that means
For each year that passes, the number of people with the common cold decreases by 203