Answer: Chris has 12 quarters and 6 dimes
Step-by-step explanation: Lets have x be the number of quarters and y be the number of nickels. If she has twice as many quarters as nickels, then we already have our first equation: x=2y! To get the second equation, you put the real world value of quarters and nickels next to their variable and have it equal the total amount of money she has ($3.30), so the equation should look like this:
.25x + .05y=3.30
The next step is easy, just solve by substituting the equations into each other! So:
If x= 2y then,
.25(2y) + .05y= 3.30
.5y + .05y= 3.30
(.55y= 3.30)÷ .55
y= 6
And if y (which is the number of nickels!) equals 6, then we can plug that back into the x= 2y equation! So:
x= 2(6)
x= 12
Thus, Chris has 12 quarters and 6 nickels! Hope this helps!