1 Answer

Felipe Belluco · Answer 1 · 2023-08-14T08:27:42+0000

Let x be the number of students in the senior class.

Four-fifths of this number x is equal to 324 based on the first sentence and the beginning of the second sentence.

So the equation to set up is
$\boldsymbol{(4)/(5)x = 324}$ and it's the same as writing
$\boldsymbol{(4x)/(5) = 324}$

If you want, you can stop reading here and attempt to solve on your own.

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On the other hand, if you want to know how to solve, then read on.

The '5' in the denominator means we're dividing 4x over 5.

To get that 5 to the other side, we'll multiply both sides by 5 to undo the division operation.

$(4x)/(5) = 324\\\\ 5*(4x)/(5) = 5*324\\\\ 4x = 1620\\\\$

Then to fully isolate x, i.e. get x all by itself, then we'll divide both sides by 4. This is to undo the multiplication of 4 onto x.

So,

$4x = 1620\\\\ (4x)/(4) = (1620)/(4)\\\\ x = 405$

This means there are 405 seniors overall.

4/5 of them went to prom, so (4/5)*405 = 324 went to prom. This confirms the answer.

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