In mathematical equations, there are constants and variables. A constant has a fixed numerical value, while a variable may be unknown or can variate. In the formula d = 2r; 2 is a constant whereas, r and d are variables. To solve the equation, you work out the problem until you define the variables. In math, once you solve variables, you can build skyscrapers or balance budgets. In science, when you isolate and know the variables, you can cure diseases or develop all sorts of effective medicines.

The point being, if you solve the problems by working out the variables until they are known constants, you’re left with a reliable formula or process, and sometimes a scientific law.