Explore Fraction Concepts with Examples and Questions

How to find f'(0) ?
${\displaystyle f\left(x\right)=\frac{x^2+3}{2x-1}}$

Write 2.25 as a fraction.

How do you simplify ${\displaystyle \frac{12}{20}}$?

I have been quite confused by the definition of functions and their uses. First of all can one define functions in a clear understandable way, with a clear explanation of their uses, how they work and what they do?
Also I have some specific questions regarding functionsLet me give you a examples:
Also I have some specific questions regarding functions
Let me give you a examples:
1. ${\displaystyle y=f\left(x\right)\Rightarrow }$ This is one of the main reasons I have difficulties understanding functions...
What does the above statement tell me, and if y is a function why do we use ${\displaystyle y=}$ at all for a formula like ${\displaystyle y=mx+b}$ would it be the same as writing ${\displaystyle f\left(x\right)=mx+b?}$
2. Something like ${\displaystyle y=x^2}$ is apparently a function... but where is the function name? Which is the input and which is the output?
3. Lastly another example: Let me suppose ${\displaystyle f=}$ distance ${\displaystyle f\left(t\right)=t^2}$
${\displaystyle f\left(2\right)=4\Rightarrow }$ Does this mean distance is 4... which is the input which is the output?
Mainly what I'm looking for in an answer is a clear and 'easy' explanation with examples to help me understand this new topic

How do you convert 7/15 into a decimal and percent?

What is 12 divided 1/4?

How do you change ${\displaystyle \frac{9}{12}}$ to simplest form?

How do you convert 1/8 into a decimal?

How do you solve ${\displaystyle x+3=5?}$

How do you change 0.2 into a fraction?

How do you write 2/5 in fraction?

How can I simplify ${\displaystyle 8^{-2}}$

What are the equivalent fractions for 3/4?

What is the percent form of 1/3?

How to solve ${\displaystyle \frac{18}{\sqrt{3}}}$ ?

Which is bigger: ${\displaystyle \frac{3}{4}\text{ or }\frac{2}{3}}$

What is 12/5 as a mixed fraction?

How do you simplify ${\displaystyle \frac{(n+2)!}{n!}?}$