To find out how much each book cost first we will subract to find out how many 2 books cost. Then we will divide. last but not least we will check our wok. Lets do it:- 
30 - 8.95 = <span>21.05
</span><span>21.05 - 7.25 = 13.80
</span>
CHECK OUR WORK:-
13.80 + 7.25 = 21.05
21.05 + 8.95 = 30
We were RIGHT!!!
Now lets divide:-
13.80 ÷ 2 = 6.90
1 book costs $6.90.
CHECK OUR WORK:-
6.90 × 2 = 13.80
We were RIGHT!!!!
So, 1 book costs $6.90.
Hope i helped ya!! 
        
                    
             
        
        
        
396.9
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Answer:
50% of 1/3: 1/2 x 1/3 = 1/6
75% of 1/2: 3/4 x 1/2 = 3/8
Step-by-step explanation:
50% = 1/2
50% of 1/3: 1/2 x 1/3 = 1/6
75% of 1/2: 3/4 x 1/2 = 3/8
 
        
             
        
        
        
Answer:
y= 2-2x
Step-by-step explanation:
Isolate y.

 
        
             
        
        
        
Step 1: Read and understand the problem statement.
You are given (time, depth) pairs of (20 s, 8 cm) and (40 s, 0 cm) and asked to write an equation that describes the relationship of depth (y) to time (x).
The rate of change is (0 cm -8 cm)/(40 s -20 s) = -8 cm/(20 s) = -2/5 cm/s. Then in point-slope form using the second point, the linear function rule is
  y = (-2/5)(x -40) +0
You can expand this to
  y = (-2/5)x +16
  y = -0.4x +16 . . . . . . using a decimal number for the slope
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If the bathtubs in your "draining race" start with the same level, the one with the steepest slope (-0.5 cm/s) will win.