Answer:
[tex]\left \{ {{n+q=28} \atop {n(0.05)+q(0.25)=4}} \right.[/tex]
And the pair [tex](n,q)=(15,13)[/tex] is the solution.
Step-by-step explanation:
We know that Yolanda paid for her movie ticket using 28 coins. She only paid with nickels and quarters.
We also know that the ticket cost $4.
We need to form a linear equation system that solves this problem.
We have the following variables :
n : number of nickels
q : number of quarters
We know that she used 28 coins ⇒ the number of nickels plus the number of quarters must be equal to 28.
We have our first equation :
[tex]n+q=28[/tex] (I)
For the second equation we need to use the ticket price information.
We know that the ticket cost $4 and she only paid with nickels and quarters.
Therefore we can write the following equation that relates the variable ''n'' and the variable ''q'' :
[tex]n(0.05)+q(0.25)=4[/tex] (II)
This equation represents that the number of nickels ''n'' per its value plus the number of quarters ''q'' per its value is equal to $4 that it is the value of the movie ticket.
With (I) and (II) we form the linear equation system :
[tex]\left \{ {{n+q=28} \atop {n(0.05)+q(0.25)=4}} \right.[/tex]
This linear equation system can be used to find the value of ''n'' and ''q''.
For example, in equation (I)
[tex]n+q=28[/tex]
we can solve it in terms of ''n'' :
[tex]n=28-q[/tex] (III)
If we use (III) in (II) :
[tex](28-q)(0.05)+q(0.25)=4[/tex]
[tex]1.4-(0.05)q+(0.25)q=4[/tex]
[tex]q(0.2)=2.6[/tex]
[tex]q=\frac{2.6}{0.2}=13[/tex]
[tex]q=13[/tex]
Now replacing this value of q in (III) :
[tex]n=28-13=15[/tex]
[tex]n=15[/tex]
We find that Yoland used 15 nickels and 13 quarters to paid the movie ticket .
