Can you make up a constructing a variable argument at the level of 8th grade math for me?

Sure! Here's an example problem for constructing and solving a variable argument at the level of 8th grade math:

Problem: The sum of five consecutive odd numbers is 135. Find the middle number.

Solution:
Let's assume the first odd number is "x." Since the numbers are consecutive odd numbers, the next four odd numbers can be represented as x+2, x+4, x+6, and x+8.

According to the problem, the sum of these five numbers is equal to 135:

x + (x+2) + (x+4) + (x+6) + (x+8) = 135

Now, we can simplify the equation:

5x + 20 = 135

Subtracting 20 from both sides of the equation:

5x = 115

To solve for x, we divide both sides by 5:

x = 23

So, the first odd number is 23. And since we need to find the middle number, we use the second representation (x+2):

23 + 2 = 25

Therefore, the middle number is 25.