Answer:
63
Step-by-step explanation:
Use Pythagorean theorem,
base² + altitude² = hypotenuse²
a² + 9² = 12²
        a² = 12² - 9² 
       a² = 144 - 81
      a² = 63
       a = √63
 
        
             
        
        
        
This problem can be solved easily by multiplying the time of the life expectancy of the coin with the fraction 1/20. The solution is as follows:
<span>Life expectancy of circulating paper money = 25 years * 1/20
</span><span>Life expectancy of circulating paper money = 1.25 years or 1 and 1/4 years</span>
        
             
        
        
        
Answer:
I think its 5 consecutive zeros.
Step-by-step explanation:
This would be a guess but I think you would need two numbers in the hundreds that also have 2 parts of which have a product of a number ending in 0, like 4 and 5.
So my guess would be 
400 * 500 * 39
= 7800000
 
        
             
        
        
        
Answer:
View explanation.
Step-by-step explanation:
The question isn't clear on whether or not you are asking if the mom or if the store is owing money to the credit card company. The store owes the full amount paid. The mom owes nothing. You can look at the images for a more detailed explanation, but it is not really needed. 
Images from https://www.creditcardinsider.com/blog/happens-credit-card-bill-make-return/