A donut shop sells a box containing cream-filled and jelly donuts for $3.16 and a box containing 4 cream-filled and 8 jelly donuts for $3.04. Find the costs of single cream-filled and jelly.

Answer 1

In order to solve this question:

Start off by setting variables to represent the cream-filled donuts and the jelly donuts.

In this case:

let x = cream-filled donuts

let y = jelly donuts

Next we will create the equation x + y = 3.16

You create this equation because there is a random number of each type of donut and the total cost comes out to $3.16. x and y represent these random variables.

Next create a second equation which looks like this: 4x + 8y = 3.04.

The 4 represents how many cream-filled donuts there are

The 8 represents how many jelly donuts there are

3.04 represents the total cost of these donuts when put together

Next we need to isolate our variables.

What I mean by this is that we have to move either the x or y variables to one side. I chose moving the y variables to the right side of the equation.

Our new equations should look like this:

1st equation: x - 3.16 = y

2nd equation: 4x - 3.04 = 8y

You can simplify the second equation by dividing by eight on both sides to remove the constant from the y variable.

New 2nd equation: 1/2x - .38 = y

Since now we have our first equation and our second equation both equal to y, we can now set both of our equations equal to each other:

x - 3.16 = 1/2x - .38

Go about this equation by solving for the x variable.

You should be left with x = 5.56

Since x represents the cream-filled donuts, this is how much the 4 cream-filled donuts cost

Plug this x value in for either the 1st equation or the 2nd equation to find out what y is equal to.

You should be left with y = 2.4

Now you set 4x = 5.56 and 8y = 2.4

Solve for the variables

Final answer:

Single Cream-filled donuts: $1.39

Single Jelly donuts: $0.3

Answer 2

8j+4c=3.04

j=30

c=16

There's more than 1 answer.

j=20

y=36

etc