Question

If 15% of x% = 1.2% ,find x?

Answer 1

`color(blue)(x=8)`

Explanation:

Rewrite as:

`15/100*x/100=1.2/100`

`x/100=1.2/100*100/15`

`x/100=1.2/15`

`x=100(1.2/15)=8`

Answer 2

`x%->x/100 = 8/100" so " x=8`

Explanation:

% is a bit like a unit of measurement but one that is worth `1/100`

So 15% is the same as:

`15" of "% ->15xx% ->15xx1/100 = 15/100`
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Applying this to the question we have:

`15%color(white)("d")ubrace(" of ")color(white)("dd")x% = 1.2%`
`color(white)("dddddd")darr`

`15/100color(white)("d.")obrace(xx) color(white)("d")x/100color(white)("d") = 1.2/100`

`(15x)/10000=1.2/100`

multiply both sides by `color(red)(10000/15)`

`color(green)((15x)/10000=1.2/100color(white)("dd") -> color(white)("dd")ubrace(15/10000color(red)(xx10000/15))xx x=1.2/100color(red)(xx10000/15)`
`color(green)( color(white)("dddddddddddddddddddddddd")darr)`
`color(white)("ddddddddddddd")->color(white)("ddd.ddddd")1color(white)("ddddd")xx x = 120/15 = 8`