Sally has seven times as many dimes as nickels. The total value of the coins is $3.00. How many nickels does she have?

the number is b. 9.6

Quotient is the number arrived at when performing division. Therefore, x is divided by 4 to get the quotient that is 12 less x.

x / 4 = 12 - x

*multiply both side by 4
4(x /4 ) = 4(12 - x)
x = 48 - 4x
*transfer like numbers
x + 4x = 48
5x = 48
*find x, divide both sides by 5
5x/5 = 48/5
x = 9.6

To check:
x / 4 = 12 - x
9.6 / 4 = 12 - 9.6
2.4 = 2.4