y=mx+b
you have TWO data points given (5,9.25) and (8, 12.25)
Find slope, m= (y1-y2) / (x1-x2)
(9.25-12.25) / (5-8) = -3/-3 = 1
so y= mx + b now becomes y = (1) x + b Substitute in one of the points to find b :
9.25 = 5 + b b= 4.25
so your equation is now
y= x + 4.25 which shows the admission is 4.25 and each sample costs 1.00