Answer: She has 40 nickels and 40 quarters .
Explanation:
Let be "n" the number of nickels Theresa has and "q" the number of quarters Theresa has.
You know that she has a total of $12 in nickels and quarters. In cents, this is:
![\$12*100=1,200\ cents](https://img.qammunity.org/2020/formulas/mathematics/middle-school/3kjrqh6umwq71me0b4y8iz4c8qhj1sa71e.png)
Then, based on this you can write the following expression:
![5n+25q=1,200](https://img.qammunity.org/2020/formulas/mathematics/middle-school/324mh3yai8sovftlqukl0m909plsuyeet5.png)
Since
, you can rewrite it as:
![5n+25n=1,200](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tfwb93ttpi4aco6otm2rcrhajgdme42ucs.png)
Solving for "n", you get:
![30n=1,200\\\\n=(1,200)/(30)\\\\n=40](https://img.qammunity.org/2020/formulas/mathematics/middle-school/iq5givo6fyms1pocmodounq7t1xx4lt0hf.png)
Therefore she has 40 nickels and 40 quarters .