Algebra
Many math problems are about physics and engineering. In many of these physics problems time is a variable. The letter used for time is . Using the basic ideas in algebra can help reduce a math problem to its simplest form making it easier to solve difficult problems. Energy is , force is , mass is , acceleration is  and speed of light is sometimes . This is used in some famous equations, like  and  (although more complex math beyond algebra was needed to come up with that last equation).