Answer: It should say either in the equation itself, or in the directions
Explanation:
If the instructions don't say which variable you're solving for, you can figure it out by looking at the equation
For example, we have this equation
In this equation, there is only one variable to solve for, and that variable is x
In this equation, there is only one variable to solve for, and that variable is y
However, if you're given an equation with more than one variable, most of the time, you have to solve for both!