All lessons › Unit 1 · Foundations

Linear equations in one variable

A linear equation in one variable looks like 3x + 5 = 20, and you find x. It shows up all the time on the Digital SAT Math section, both as plain equations and as word problems where you write the equation yourself.

This lesson starts with the balance idea, then moves to parentheses, x on both sides and word problems. Last, you learn how to tell if an equation has one answer, none or infinitely many, which the SAT often asks about. Every step is animated, each part has a quiz, and there are practice questions.

In this lesson

• Solving with a balance
• Brackets and x on both sides
• Equations from word problems
• How many solutions