To know about independent and dependent variable, first we have to know about variables.
In mathematics, a variable is an event, idea, period or a type of category which we trying to measure. So we can say that a variable is anything that can be changed, like time,height,weight, attention etc.
In mathematics, we have two types of variables, independent variable and dependent variable. These two variables are the mathematical tools, used in an experiment. By the use of these tools, we control over the experiment and measure the result. These variables are related to one another.