Please, take a look at WolframAlpha API documentation page:
I would like to have web application (Java?), which would work following way:
1. Gets query from user, using input form on my page (like here: https://blog.etrapez.pl/narzedzia/kalkulator-do-rownan-rozniczkowych/ ).
2. Sends the query to WolframAlpha using WolframAlpha API (https://products.wolframalpha.com/api/).
3. Gets the results and outputs the results in appropriate form back to the user.