Pizzas are circles. Area of circles is (pi)r^2. 
Then find the cost per in.^2 
Smallest cost per in.^2 is better buy.
        
                    
             
        
        
        
9514 1404 393
Answer:
   18
Step-by-step explanation:
Solve the first for a, then substitute into the second.
   a = 27/(5b^2)
Then ...
   (27/(5b^2))^2·b = 135
   27^2/(5^2·135) = b^3 = 27/125
   b = ∛(27/125) = 3/5
   a = 27/(5(3/5)^2) = 15
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The expression of interest is ...
   a +5b = 15 + 5(3/5) = 15 +3
   a +5b = 18
 
        
             
        
        
        
(8x-10)°+(6x)°+(10x+10)°=360°
8x-10+6x+10x+10=360
8x+6x+10x-10+10=360
24x-10+10=360
24x=360
24x/24=360/24
x=15
Scalene because all three sides are different.
        
             
        
        
        
I think it is 9 - x because 81-x^2/9-x = 9-x