I was working on tactics this afternoon and I thought it was just a problem with my mobile app. The subtraction shows on the website too. Is there something I'm missing?

Both the app and website Tactics Trainer evaluates you on both the solution and the time it took you to find the solution.

How long did it take you to succeed in passing the problem? You can go dowm if you take to long on a problem.

I'm an absolute beginner, so it took me a while. Thanks for your help. I'll have to keep practicing and get my speed up!