Im confused that's all - if 80% is 75 marks, what is full marks

Let the full marks be represented by = x

As given, 80% of x is 75

So,

x=

x=93.75

Hence, full marks is 93.75

We can check also- =75

-8/2y-8=5/y+4-7y+8/y^2-16

we move all terms to the left:

-8/2y-8-(5/y+4-7y+8/y^2-16)=0

we can not solve this equation