RULE-OF-THREE

The best way to explain what the app does is to think that you need to know how much is the 23 % of 1500 pounds, you just put 100(x1) is a 1500 like 23 is a, then the app calculate this automatically, see picture one. Other good example imagen that you have a construction and you know that 20 worker finishing a building in 10 days, but you need it to finished in 5, so how many workers do you need ??. Just put 10 in variable x1 , 20 in z1 and 5 in x2, see picture 2