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Exercises Numbers, fractions and percents

Example 6.43 from Prealgebra, 6.5 Solve Proportions and their Applications

Solve Proportions and their Applications: example 6.43

Solve: $\frac{144}{a} = \frac{9}{4} .$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
Notice that the variable is in the denominator, so we will solve by finding the cross products and setting them equal.

Find the cross products and set them equal.

Simplify.

Divide both sides by 9.

Simplify.

Check your answer.

Show common factors..

Simplify.

Another method to solve this would be to multiply both sides by the LCD, $4 a .$ Try it and verify that you get the same solution.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Solve the proportion: $\frac{91}{b} = \frac{7}{5} .$

How did it go?

PreviousSolve Proportions and their Applications: example 6.42 Next Solve Proportions and their Applications: example 6.44

From Prealgebra (1st edition) by OpenStax (Rice University), section 6.5, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.