An equation in math is a statement stating that two math expressions are equal. An equation always consists of an equal sign. The equal sign in an equation is read as "this equals that."

An example of an equation is 9x + 5 = y. The letters x and y in the equation are called variables. These represent unknown values, which are discovered through solving the equation. The number 5 in this equation is known as a constant, due to it being a number on its own. The 9 in this equation is a coefficient, a number multiplied by a variable. The plus sign is the operator of the equation, showing which operation to perform in the equation.