Math master - new kind of brainstorm

Last time I asked you, whether you like geometry? I will not repeat my question second time. Today's  fresh apple application concerns algebra. You already scared? No? But you should. This application is able to put math geniuses on their knees! And I'm quite serious. As with all heavy applications, in this case - three difficulty levels.

It begins with a light brainstorm. Can you simultaneously hold in mind two numbers that need to be add (subtract, there is no such hardcore as, multiply and divide but maybe in a paid version) and the correct answer which in this case will turn out? Managed with this? Then more difficult level waits for you.

Now you must remember once all the existing options, and then find them one by one among the many closed squares. And if you managed to survive in this case too, you're pass in the final test. Your time is quickly leaves,  but there are many examples and options. It was hard, I was sweating, but succeeded. I wish you will succeed too. I hope you understand the humor.