Hello!
An equivalent fraction is a fraction that is equal to another but is just written different. For example 1/2 and 3/6. They are both one half of the whole. 3/6 is just put into smaller pieces, but they equal the same thing.
I hope this helps!
From the slope form of a line;

y-b=bx-ab
y=bx-ab+b
y=bx-b(a-1)
I think 50% or 1/2 ( it’s the same just one is in fraction and other in percentage)
The answer for the following question is A) -b