To find the number of grapes Reza ate yesterday using equivalent ratios, we start with the information given: today, Reza ate 20 grapes, which is 400% of the number of grapes he ate yesterday.
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Understand the percentage: A percentage means a part per hundred. So, when we say that Reza ate 400% of the grapes he ate yesterday, it indicates that he ate four times the amount he ate yesterday.
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Set up the ratio: Let \( x \) represent the number of grapes Reza ate yesterday. According to the problem, 400% of \( x \) is equal to 20 grapes. We can express this mathematically as: \[ 400% \times x = 20 \] Since 400% can also be expressed as 4 (because 400% = 400/100 = 4), we rewrite the equation: \[ 4x = 20 \]
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Solve for \( x \): To find \( x \), we divide both sides of the equation by 4: \[ x = \frac{20}{4} = 5 \]
Thus, Reza ate 5 grapes yesterday.
Summary: By understanding that 400% is equivalent to 4 times the amount, we set up an equation, used division to isolate \( x \), and determined that Reza ate 5 grapes yesterday.
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