About this calculator
The Solve for Unknown Fraction Calculator solves proportion equations such as x/3 = 4/6. It shows cross multiplication so students can see how the unknown value is isolated.
unknown fraction calculator method
Fraction equations are solved by cross multiplying. After multiplying across the equals sign, rearrange the equation so x is on its own.
- x/a = b/c -> cx = ab -> x = ab/c
- a/x = b/c -> bx = ac -> x = ac/b
- a/b = x/c -> bx = ac -> x = ac/b
How to use the unknown fraction calculator
- Choose where x appears in the equation.
- Enter the known values.
- Cross multiply the fractions.
- Write the equation containing x.
- Divide both sides by the coefficient of x.
- Check the answer by substituting it back into the equation.
Worked examples
Solve x/3 = 4/6
Input: x/3 = 4/6
Calculation: 6x = 12
Result: x = 2
Solve 5/x = 10/8
Input: 5/x = 10/8
Calculation: 10x = 40
Result: x = 4
Cross multiplication
Cross multiplication works for proportions because both sides of the equation are equal fractions.
Checking the answer
Substitute x back into the original equation. If both fractions simplify to the same value, the solution is correct.
Learning and homework note
This calculator is for learning, checking, and general educational use. It shows the method so students can compare each step with their own working, but it should not replace learning the underlying fraction rules.
- Check that every denominator is not zero.
- Negative fractions can be written in more than one equivalent form.
- Rounding may affect decimal or percentage displays.
Frequently asked questions
Does this show the working?
Yes. The fraction calculators are designed to show the main steps, not just the final answer.
Does it simplify answers?
Yes. Fraction answers are reduced to lowest terms where simplification is part of the method.
Can denominators be zero?
No. A denominator of zero is undefined in fraction arithmetic.
Can I use negative fractions?
Yes, but pay attention to signs. The calculator normalises signs so the denominator stays positive.
Why might my teacher write the answer differently?
Equivalent fractions and mixed numbers can represent the same value. Check whether the question asks for improper fraction, mixed number, decimal, or simplest form.
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