Rational numbers are a giant group of numbers in mathematics. Basically, rational numbers are all numbers that can be written as a fraction. The set of rational numbers includes many subsets of numbers which are provided in the image.
 
        
             
        
        
        
Answer:
56 coins for 0.50 cents
Step-by-step explanation:
 
        
             
        
        
        
Answer:
It is not well defined. 
Step-by-step explanation:
Because set is a collection of well defined objet. And matter contains of solid, liquid and gas
 
        
             
        
        
        
The system of equations to find the cost of one adult ticket, a, and the cost of one child ticket, c are Roy's; 6a+2c=66 Elisa's 5a+4c=62.
<h3>What is a system of equations?</h3>
A system of equations is two or more equations that can be solved to get a unique solution. the power of the equation must be in one degree.
Let's consider adults tickets be a and child tickets be c
so
Roy's purchase
6a+2c=66------1
Elisa's purchase
5a+4c=62-------2
Hence,  the system of equations
6a+2c=66------1
5a+4c=62-------2
solving simultaneously
6a+2c=66
5a+4c=62
Also,
  12a+4c=132
 -5a+4c=62
   7a=70
a=$10
put  a=70 in 1
6(10)+2c=66
60+2c=66
2c=66-60
2c=6
c=$3
Learn more about equations here;
brainly.com/question/10413253
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