Sure, let's solve this problem step by step.

First, let's denote the cost of a DVD as D and the cost of a book as B.

From the problem, we can form two equations:

1) 3D + 4B = 40 (This is from David's purchase)
2) D + 6B = 18 (This is from Anna's purchase)

Now, we can solve this system of equations.

Let's multiply the second equation by 3:

3D + 18B = 54

Now, let's subtract the first equation from this new equation:

3D + 18B - (3D + 4B) = 54 - 40
14B = 14
B = 14/14 = 1

So, each book costs $1.

Now, let's substitute B = 1 into the second equation:

D + 6*1 = 18
D = 18 - 6 = 12

So, each DVD costs $12.

Therefore, the cost of each DVD is $12 and the cost of each book is $1.

Question

Sure, let's solve this problem step by step.

First, let's denote the cost of a DVD as D and the cost of a book as B.

From the problem, we can form two equations:

1) 3D + 4B = 40 (This is from David's purchase)
2) D + 6B = 18 (This is from Anna's purchase)

Now, we can solve this system of equations.

Let's multiply the second equation by 3:

3D + 18B = 54

Now, let's subtract the first equation from this new equation:

3D + 18B - (3D + 4B) = 54 - 40
14B = 14
B = 14/14 = 1

So, each book costs $1.

Now, let's substitute B = 1 into the second equation:

D + 6*1 = 18
D = 18 - 6 = 12

So, each DVD costs $12.

Therefore, the cost of each DVD is $12 and the cost of each book is $1.

Knowee AI · Accepted Answer