Initially it will only be the answer from the previous maths question that you need to remember.
Then a new square will appear with a new equation. You will need to solve this new equation, and at the same time remember the old one.
Next the old square will appear on the left, and you will need to remember the answer from before.
Then the right square will appear once more, and you will have to solve the old right equation. This is very tricky, and takes practice.
You are solving and remembering two different systems of equations in parallel.