Answer: 11 quarters.
Solution:
The first thing I did was establish a “key”, saying that y=#of quarters; x=#of dimes
We know that there are three times as many dimes as quarters. So we can state that x=3y.
Then we say that 25y + 10x = 605
(Value of coin * amount of coins)
Then we plug x=3y into the equation, yielding:
25y + 10(3y) = 605
=> 25y + 30y = 605
=> 55y = 605
=> 605/55 = 11 = y
[note: if you wanted to find the number of dimes plug y=11 into our x=3y equation.
33 dimes]
Hope this helps, my work is attached :)
