Kelly has 24 dimes and quarters worth $3.60. How many quarters does she have?

Step-by-step explanation:

Let x = # of dimes

Let y = quarters

Using these variables, we can set up equations. One that represents the number coins, and the other to represent the total amount.

x + y = 24 eq1

0.10x + 0.25y = 3.60 eq2

We can use the substitution method. Substitute eq1 into eq2. Since we want to know the number of quarters, we need to get eq2 in terms of only y. From eq1,

x = 24 - y

Eq2 now becomes

0.10 (24 - y) + 0.25y = 3.60

Solve for y from this equation.

For the elimination process:

Multiply eq1 by 0.10. Keep eq2.

0.10x + 0.10y = 2.4 eq1

0.10x + 0.25y = 3.60 eq2

Next, you can subtract eq2 from eq1 to eliminate the x terms.

-0.15y = - 1.2

Now solve for y. I let you take it from here.

Should be around 5 (five) quarters