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If 9% of a number is 18, what is the number?

1 Answer

Feb 6, 2017

The number is $200$ $200$

Explanation:

Let the number be $x$ $x$

$9$ $9$ percent of the number means
$XXX \frac{9}{100} \times x$ $color(white)("XXX")9/100 xx x$

So if $18$ $18$ is $9$ $9$ percent of the number:
$XXXXXXXXXX 18 = XXXX \frac{9}{100} \times x$ $color(white)("XXXXXXXXXX")18=color(white)("XXXX")9/100 xx x$

$XXX \to \frac{100}{9} \times 18 = \frac{100}{9} \times \frac{9}{100} \times x$ $color(white)("XXX")rarr 100/9 xx 18 = 100/9 xx 9/100 xx x$

$color(white)("XXX")rarr 100/cancel(9) xx cancel(18)^2 = cancel(100)/cancel(9) xx cancel(9)/cancel(100) xx x$

$color(white)("XXX")rarrcolor(white)("XXXXX")200 = color(white)("XXXXXXXXX")x$

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