If 5 is to 20 as x is to 80, what is x?

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Multiple Choice

If 5 is to 20 as x is to 80, what is x?

Direct proportion is at work: the two pairs keep the same ratio. Since 5 corresponds to 20, the ratio is 20/5 = 4. So x must pair with 80 to have the same ratio, meaning 80/x = 4. Solving gives x = 80/4 = 20. Therefore, x is 20. If you test other values, you’ll see they don’t maintain the 1:4 ratio (for example, a pair like 40:80 is 1:2, not 1:4).

Direct proportion is at work: the two pairs keep the same ratio. Since 5 corresponds to 20, the ratio is 20/5 = 4. So x must pair with 80 to have the same ratio, meaning 80/x = 4. Solving gives x = 80/4 = 20. Therefore, x is 20. If you test other values, you’ll see they don’t maintain the 1:4 ratio (for example, a pair like 40:80 is 1:2, not 1:4).

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