I've just come back from a shopping trip to New York. While I was out there I purchased 2 pairs of UGG boots on my mastercard; 1 pair for myself at $180 and a pair for my sister at $140. I checked my online banking today and it has converted to £222.82, trouble is I'm really rubbish at maths and can't work out the exchange rate that has been used with my bank. I need to know urgently so that my sister can pay me back tomorrow.
Tripe - all you need is someone with a calculator able to understand that the required maths is (£222.82*140)/(140+180).
It is absolutely nothing to do with currency conversion - the Mastercard people did that conversion already.