Linear Equations in One Variable
Solving an equation means finding the value that keeps both sides equal — like a balance scale. Whatever you do to one side, you must do to the other. Drag the slider to find the value of x that balances the scale.
Think of an equation as a balance scale: the expressions on each side of the equals sign must always weigh the same. To isolate x, undo whatever’s been done to it — in reverse order — by applying the same operation to both sides so the scale stays balanced.
For 2x + 3 = 11: first undo the +3 by subtracting 3 from both sides, leaving 2x = 8. Then undo the ×2 by dividing both sides by 2, leaving x = 4.
On the SAT, these show up as straightforward “solve for x” questions, but also hidden inside word problems and multi-step equations with parentheses or variables on both sides — the same balancing logic applies no matter how the equation is dressed up.
Unlimited practice. The generator below builds a fresh ax + b = c equation every time — pick a difficulty and keep going for as long as you want. The wrong answers aren’t random noise; they’re built from the same mistakes above, like sign slips and stopping one step early, so getting one wrong tells you something real about where the error crept in.