# Thread: Algebraic Expression

1. ## Algebraic Expression

I have absolutely no idea how to work out the algebraic expression(s) to solve this problem.

2 times x is subtracted from 200. The difference is then increased by 20%. If the overall result is equal to decreasing x by 40%, find x.

I desperately need your help.

peter

2. Let's write it out. Originally Posted by Peter I have absolutely no idea how to work out the algebraic expression(s) to solve this problem.

2 times x is subtracted from 200.
Write it out: $\displaystyle 200-2x$

The difference is then increased by 20%.
Write it out again: $\displaystyle 1.2\times\left(200-2x\right)$

If the overall result is equal to decreasing x by 40%, find x.
So: $\displaystyle 1.2\times\left(200-2x\right)=0.6x$

Divide both sides by 0.6 to get: $\displaystyle 2\times\left(200-2x\right)=x$

Remove the parenthesis: $\displaystyle 400-4x=x$

Add 4x to both sides: $\displaystyle 400=5x$

Divide both sides by 5: $\displaystyle 80=x$

BUT CHECK MY ARITHMETIC!!!

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