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 Dependent Variable

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# Solving Proportions Using Cross Multiplication

 Letâ€™s consider this proportion: To clear the fractions, we multiply both sides by bd, the LCD of the fractions. To simplify each side, we cancel common factors. The result is: ad = bc Now look again at the original proportion. We draw a line from a to d, and draw a line from b to c. The lines form a â€œcrossâ€ and we obtain the previous result: ad = bc

This process is often called cross multiplication.

Definition â€” Cross Multiplication

To clear the fractions from a proportion, multiply the numerator of each fraction by the denominator of the other fraction.

That is, is equivalent to ad = bc.

Example 1

Solve the proportion for x:

 Solution Cross multiply. Divide both sides by 26. Simplify. 26xx = 5 Â· 182 = 35

We leave the check to you.