A coin purse contains d dimes and q quarters. There are 35 coins in the purse, and the total value of the coins is $5.60. Create the system of linear equations and use it to find how many dimes and quarters are in the purse.

Respuesta :

Answer:

14 dimes, 21 quarters

Step-by-step explanation:

Represent dimes with d and quarters with q.

So: 35 coins means

[tex]d + q = 35[/tex]

1 dime = $0.10 and 1 quarter = $0.25. So, a value of $5.60 means

[tex]0.10d + 0.25q = 5.60[/tex]

So, the system of equations is:

[tex]d + q = 35[/tex]

[tex]0.10d + 0.25q = 5.60[/tex]

Make d the subject in [tex]d + q = 35[/tex]

[tex]d = 35 - q[/tex]

Substitute 35 - q for d in [tex]0.10d + 0.25q = 5.60[/tex]

[tex]0.10d + 0.25(35 - q) = 5.60[/tex]

Open bracket

[tex]0.10d + 8.75 - 0.25q = 5.60[/tex]

Collect Like Terms

[tex]0.10d - 0.25q = 5.60 - 8.75[/tex]

[tex]-0.15q = -3.15[/tex]

Solve for q

[tex]q = \frac{-3.15}{-0.15}[/tex]

[tex]q = 21[/tex]

Substitute 21 for q in [tex]d = 35 - q[/tex]

[tex]d = 35 - 21[/tex]

[tex]d = 14[/tex]