Number 16 is 13.5 because each half triangle is 1 unif square
        
             
        
        
        
Answer:
79
Step-by-step explanation:
171-1-91=170-91=79
 
        
             
        
        
        
=48 
Multiply by 1
Add 1 1 11 11
 to both sides of the equation
 
        
                    
             
        
        
        
6.8,6.827,6.86,6.9
1.2,1.203,12.03, 12.301,12.31
        
             
        
        
        
y = ( 3 * x ) - 2.
This is because the card costs for 3 $ and should be multiplied by the number of total cards she buys in that particular day. So 3 * x. 
Now as she has got a 2$ off coupon, whatever the total is she gets 2 dollars off on that price. So we will subtract 2 at that time. FInally all this summed up would be equal to y.