Math  /  Algebra

QuestionSelect the correct answer.
Kevin has $4.85\$ 4.85 in nickels and dimes. If he has 34 fewer dimes than nickels, how many coins (nickels and dimes) does he have altogether? A. 74 coins B. 75 coins C. 76 coins D. 77 coins

Studdy Solution

STEP 1

What is this asking? How many nickels and dimes does Kevin have if he has $4.85\$4.85 total, and 3434 fewer dimes than nickels? Watch out! Don't mix up the values of nickels (55 cents) and dimes (1010 cents)!

STEP 2

1. Set up variables and equation
2. Solve for the number of nickels
3. Solve for the number of dimes
4. Calculate the total number of coins

STEP 3

Let nn be the number of **nickels** and dd be the number of **dimes**.
We know a nickel is worth $0.05\$0.05, and a dime is worth $0.10\$0.10.

STEP 4

We're told Kevin has $4.85\$4.85 in total.
We can write this as an equation: 0.05n+0.10d=4.850.05n + 0.10d = 4.85 This equation represents the **total value** of his coins.

STEP 5

We also know he has 3434 fewer dimes than nickels.
Mathematically, this means: d=n34d = n - 34 This equation relates the **number** of nickels and dimes.

STEP 6

Now, let's **substitute** the second equation into the first equation.
This way, we get an equation with only one variable, nn: 0.05n+0.10(n34)=4.850.05n + 0.10(n - 34) = 4.85

STEP 7

**Distribute** the 0.100.10: 0.05n+0.10n3.40=4.850.05n + 0.10n - 3.40 = 4.85

STEP 8

**Combine** the nn terms: 0.15n3.40=4.850.15n - 3.40 = 4.85

STEP 9

**Add** 3.403.40 to both sides of the equation: 0.15n=4.85+3.400.15n = 4.85 + 3.40 0.15n=8.250.15n = 8.25

STEP 10

**Divide** both sides by 0.150.15 to find nn: n=8.250.15n = \frac{8.25}{0.15} n=55n = 55So, Kevin has **5555 nickels**!

STEP 11

We know d=n34d = n - 34, and we just found that n=55n = 55.
Let's **substitute** n=55n = 55 into this equation: d=5534d = 55 - 34 d=21d = 21Kevin has **2121 dimes**!

STEP 12

To find the total number of coins, we simply **add** the number of nickels and dimes: 55+21=7655 + 21 = 76

STEP 13

Kevin has a total of 76\textbf{76} coins.
So the correct answer is C.

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