Algebra 1 · Solving linear equations

How to Solve an Equation with a Fraction

Problem

x3+2=5\frac{x}{3} + 2 = 5

Answer

x=9x = 9

A fraction in an equation is a division waiting to be undone. Isolate the fraction, then multiply both sides by its denominator.

Step-by-step solution

  1. Subtract 2 from both sides to undo the addition.

    x3=3\frac{x}{3} = 3

    Why: Undo addition and subtraction before multiplication and division.

  2. Multiply both sides by 3 to clear the fraction.

    3×x3=3×33 \times \frac{x}{3} = 3 \times 3

    Why: Multiplying by the denominator undoes the division.

  3. Simplify both sides.

    x=9x = 9

    Why: The 3s cancel on the left.

  4. Check the answer in the original equation.

    93+2=3+2=5\frac{9}{3} + 2 = 3 + 2 = 5

    Why: The check confirms that the two sides are equal.

Common mistakes

  • Multiplying only x/3 by 3. Every term must be multiplied.
  • Adding 3 to the denominator instead of multiplying.
  • Dividing by 3 instead of multiplying. The fraction already divides by 3.

Practice problems

Use the same method. Work each problem on paper, then open the answer to check.

  1. x4+3=7\frac{x}{4} + 3 = 7

    Show answer

    x=16x = 16

  2. x5−1=4\frac{x}{5} - 1 = 4

    Show answer

    x=25x = 25

  3. 2x3=8\frac{2x}{3} = 8

    Show answer

    x=12x = 12

  4. x2+x3=5\frac{x}{2} + \frac{x}{3} = 5

    Show answer

    x=6x = 6

  5. 3−x4=13 - \frac{x}{4} = 1

    Show answer

    x=8x = 8