Let's define the variables for the prices of the textbooks:
Let \( x = \) the cost of the first textbook
Let \( y = \) the cost of the second textbook
Now we can write the equations based on the provided statements:
-
Two of Julie’s textbooks are a total of $65:
\[
x + y = 65
\]
-
The difference in price between the two books is $9:
\[
x - y = 9 \quad \text{(assuming the first book is more expensive)}
\]
Now we can summarize:
Let \( x = \) the cost of the first textbook
Let \( y = \) the cost of the second textbook
The equations are:
- \( x + y = 65 \)
- \( x - y = 9 \)
Solving the equations
We can use the first equation to express \( y \) in terms of \( x \):
\[
y = 65 - x
\]
Now, substitute \( y \) in the second equation:
\[
x - (65 - x) = 9
\]
Simplify:
\[
x - 65 + x = 9
\]
Combine like terms:
\[
2x - 65 = 9
\]
Add 65 to both sides:
\[
2x = 74
\]
Divide by 2:
\[
x = 37
\]
Now substitute \( x \) back to find \( y \):
\[
y = 65 - x = 65 - 37 = 28
\]
Final Answer:
The cost of the first textbook is $37, and the cost of the second textbook is $28.
So,
Let \( x = 37 \) (cost of the first textbook)
Let \( y = 28 \) (cost of the second textbook)