# Pre-Algebra Practice Questions: Cross-Multiply to Solve Equations

When an algebraic equation contains fractions, you can use cross-multiplication to solve the equation. The following practice questions contain two equal fractions, where you need to cross-multiply to solve them.

## Practice questions

- Rearrange the equation
to solve for

*x*. - Solve the equation

## Answers and explanations

*x*= –4Remove the fraction from the equation by cross-multiplying:

Multiply to remove the parentheses from the left side of the equation:

8

*x*+ 40 = –2*x*At this point, you can solve for

*x*:*x*= 5Remove the fractions from the equation by cross-multiplying:

Remove the parentheses from the left side of the equation by multiplying through by

*x*; remove parentheses from the right side of the equation by FOILing:4

*x*^{2}– 7*x*= 4*x*^{2}– 10*x*+ 6*x*– 15Rearrange the equation:

4

*x*^{2}– 7*x*– 4*x*^{2}+ 10*x*– 6*x*= –15Notice that the two

*x*^{2}terms cancel each other out: