Answer:
He has 11 quarters
Explanation:
* Lets study the information in the problem to solve it
- The value of dimes and quarters is $6.35
- There are dimes and quarters
- The dime = 10 cents
- The quarter = 25 cents
* We must change the money from dollars to cents
∵ $1 = 100 cents
∴ $6.35 = 6.35 × 100 = 635 cents
- The number of dimes = 3 + 3 × number of quarters
* Let number of dimes is D and number of quarter is Q
∴ D = 3 + 3Q
∴ 10D + 25Q = 635
* Substitute the value of D from first equation in the second equation
∴ 10(3 + 3Q) + 25Q = 635 ⇒ open the bracket
∴ 10(3) + 10(3Q) + 25Q = 635
∴ 30 + 30Q + 25Q = 635 ⇒ collect like terms
∴ 30 + 55Q = 635 ⇒ subtract 30 from both sides
∴ 55Q = 605 ⇒ divide both sides by 55
∴ Q = 11
* He has 11 quarters