You see an equation like 'x + y = 10'. How do you solve for two variables? The shocking truth: you can't.

A single equation with two variables has an infinite number of solutions. It defines a relationship, not a specific answer.

For example, if x=1, y=9. If x=2, y=8. If x=100, y=-90. The possibilities are endless.

All of these solutions lie on a straight line when you graph them. The line *is* the solution set.

To find a single, unique solution for two variables, you need a second, different equation that is also true.

This is called a 'System of Equations.' For example: x + y = 10 AND x - y = 2.

Now you have two truths, two constraints. There is only one pair of numbers in the universe that makes both statements true.

You can solve this system using methods like substitution or elimination.

In this case, the only solution is x=6 and y=4.

Remember the golden rule: To find a unique solution, you need as many equations as you have variables.