To find 80% of a $200 phone bill using equivalent ratios, you can follow these steps:
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Understand what a percentage means: The term "80%" can be converted into a fraction. 80% means 80 out of 100, or \( \frac{80}{100} \).
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Set up the equivalent ratio: We're interested in finding 80% of $200, which can be modeled with the ratio of part to whole: \[ \frac{80}{100} = \frac{x}{200} \] Here, \(x\) represents the amount that corresponds to 80% of the $200.
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Cross-multiply: To find \(x\), cross-multiply the two ratios: \[ 80 \times 200 = 100 \times x \]
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Calculate: Perform the multiplication on the left side: \[ 16000 = 100x \]
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Solve for \(x\): Now, divide both sides by 100 to isolate \(x\): \[ x = \frac{16000}{100} = 160 \]
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Conclusion: Thus, 80% of the $200 phone bill is $160.
In summary, by setting up the equivalent ratio and performing some algebra, we've found that 80% of $200 is $160.