Most teachers will write it off as obvious. Taking a percentage of something is just multiplication and if you actually write it down with multiplication, it is, indeed, obvious:

4*75/100=75*4/100

And yes, it means you can just multiply 75 by 4 first and then divide by 100.

I must inform you, the bug is very much black under the mask.

There is a category of Russian memes known as “волчьи мемы” (literally “wolf’s memes”) where you have a picture of a wolf, often distorted, put some cliche edgy text on it, but swap some words to make it into something hilarious.

√∞ = ∞

I’m very sorry you had to go through such stupid school tests, welcome to the real world. sqrt(x) is just a shorthand for x^(1/2).