# Percentage Calculation Problem

I have some financial reports, I can see user deposits of:

£12.90

But actually, the real deposit is £15, but because of fees which I've worked out is 14%, it brings it down to £12.90.

On my report I can see numerous deposits such as

£12.90
£8.60


But when I try to add 14% on to these values it doesn't give me the correct answer

e.g. 14% of £12.90 = £1.80 + £12.90 = £14.70


How would I do the calculation from the deposits in my report to get the correct answer.

I hope this is explained well.

• The $14\%$ is taken off the total, not the discounted value. Thus, given $12.90$ you should divide by $1-.14=.86$. (and $\frac {12.9}{.86}=15$ as desired).
– lulu
Nov 11, 2016 at 22:09
• That works perfectly - but is where has the .14 come from? Nov 11, 2016 at 22:11
• $14\%$ is $.14$. After all $.14\times100=14$.
– lulu
Nov 11, 2016 at 22:11
• Dam, now I feel stupid - thanks for explaining this for me Nov 11, 2016 at 22:12
• The way the algebra sorts out: you start with $x$ and remove $14\%$ of it, thus retaining $x-.14x=(1-.14)x=.86x$. You are then told that this is $12.9$ so we have $.86x=12.9\implies x = \frac {12.9}{.86}=15$.
– lulu
Nov 11, 2016 at 22:13

When you have $12.90$ pounds then they are equal to $86\%$. $14\%$ have been already subtracted (from $100\%$).
To get $100\%$ you have to divide $12.90$ by $86$. Now you have $1\%$ from $100\%$.
The result has to be multiplied it by $100$ to get $100\%$.
$12.90\cdot \frac{100}{86}=15.00$
$15$ pounds are equivalent to $100\%$