### Some Algebra For The Day

High school math is an awesome gift, if you remember how to use it.

The thing is, I have R380 in eBucks and apparently qualify for a 20% discount. So I needed to figure out how much money I can claim to have, then activate the 20% to end up at R380. So I wrote this equation:

x - 0.2x = 380

The trouble is I forgot that x is actually a whole and taking away 0.2 of x leave you with 0.8x and 380 divided by 0.8 is 475, ie:

0.8x = 380 (4/5)x = 380 // convert decimal fraction to proper fraction 4x = 1900 // multiply both sides by 5 x = 475 // divide both sides by 4, and et voila

Simple, right? Except, as I said I forgot that x subtraction part. I was eventually helped by a cool website aptly named algebrahelp.com which did this form me:

Simplifying x + -1(x * 0.2) = 380 Reorder the terms for easier multiplication: x + -1(0.2x) = 380 Remove parenthesis around (0.2x) x + -1 * 0.2x = 380 Multiply -1 * 0.2 x + -0.2x = 380 Combine like terms: x + -0.2x = 0.8x 0.8x = 3800 Solving 0.8x = 380 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Divide each side by '0.8'. x = 475 Simplifying x = 475

So, I should be able to pay for R475 item with R380. The tough part convincing a merchant that I have enough eBucks, well, technically.

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