Question

In one day, a book store earned $199 in sales for 4 copies of a new cookbook and 5 copies of a new science fiction novel. On the next day, it earned $152 in sales for 3 copies of the cookbook and 4 copies of the science fiction novel. What was the price of each book?

Answer 1

Answer:

The cookbook costs $36 per copy while the science fiction costs $11 per copy

Step-by-step explanation:

Here in this question, we are interested in calculating the price of the cookbook and the price of the science fiction novel.

Since we do not know the price of each, we start by assigning variables to stand in for these unknown prices.

Let the price of the cookbook be $x , while the price of the science fiction be $y

Now, on the first day, 4 copies of the cookbook and 5 copies of the fiction;

mathematically that would be 4 * x and 5 * y

We add both and sum to be $199

Thus we have;

4x + 5y = 199 ••••••••••(i)

On the second day;

3 copies of cookbook 3 * x = 3x with 4 copies of science fiction 4 * y

Adding both yielded 152;

Thus, we have ;

3x + 4y = 152••••••••••(ii)

So we need to solve both equations simultaneously to get the values of x and y

4x + 5y = 199

3x + 4y = 152

Multiply equation i by 3 and equation ii by 4

3 * 4x + 5y = 199

4 * 3x + 4y = 152

12x + 15y = 597

12x + 16y = 608

Now, subtract multiplied equation ii from multiplied equation i

(12x-12x) + (15y-16y) = (597-608)

-y = -11

y = 11

To get x, simply substitute in any of the equations;

let’s use equation 1

4x + 5y = 199

4x + 5(11) = 199

4x + 55 = 199

4x = 199-55

4x = 144

x = 144/4

x = 36