The Universal Calculation Engine
The Universal Calculation Engine

You know the total and one part need the other

Part of: Solving Equations

A typical equations problem: read what is asked before you calculate.

What to do first

For equations, list knowns and unknowns. Check whether the problem wants a number, a relationship, or a graph. Solving Equations is the reference lesson.

Read the question

Wrong answers on equations often come from answering a different question than the one asked, especially “how many” versus “how much is left.”

Total and parts

You know a total and one part; you need the other part. Subtract the known part from the total, or write total = part₁ + part₂ and fill in what you know.

Sense-check

Core lesson

Related: Solving Equations. Use the calculator with your own numbers when the example is not close to your case.

Use the calculator

FAQ

Where is the main lesson?

Solving Equations has the full topic, examples, and practice links.

Which calculator first?

After your setup is on paper, open Linear & quadratic equation for a quick numeric pass.