.
a coin bank contains dimes and quarters there are 22 coins in the bank with a value of $3.25 how many dimes and how many quarters
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Your equations are
d + q = 22, (1)
10d + 25q = 325. (2)
where d is the number of dimes and q is the number of quarters.
Express d = 22-q from (1) and substitute it into (1). You will get a single equation for the unknown q
10*(22-q) + 25q = 325.
Simplify it:
220 - 10q + 25q = 325 ---> 15q = 325 -220 ---> 15q = 105 ---> q= = 7.
Answer. The coin bank contains 7 quarters and 22-7 = 15 dimes.