$40=T >?=m
T= $40,$80,$120,etc.
m=1,2,3,etc
Answer:

Step-by-step explanation:
the minimum of f is for x = 1 and f(1)=0
f is decreasing for x<=1 and increasing for x>=1
so the domain is 

x>=1 so x is positive and we can take the square root
so 
That would be a total of 32