A negative number in this wouldn't be applicable.
Johnny started out with $2,745 in the beginning, EARNING (This being the key word) interest each year. Therefore, he comes out with $39,974, not being a negative number. 
Hope I helped! ^-^
        
             
        
        
        
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(-4)(-2)= 8
8(-5)= -40
Answer: -40
        
             
        
        
        
Answer:
See below.
Step-by-step explanation:
Let's look at the cost for members (C1) first.  Let x be the number of visits.
C1(x) = 12 + 8x
For non-members (C2), we can do the same.
C2(x) = 10x
You can graph these two equations.
x        C1         C2
0       12          0
1        20        10
2       28        20
3       36        30
4       44        40
5       52        50
6       60        60
7       68        70
Let's make the two equations equal, to find out where the benefit is the same.
12 + 8x = 10x
2x = 12
x = 6
Up to 5 visits, the non-member cost is better.  At 6 visits, there's the same price.  For more than 6 visits, the member cost is better.