PLS HELP OR I WILL FAIL I BEG U HELP

Answer:
The first one, you cannot factor because the two values do not share any common factors. Hence, the answer would just be:
a. 51x-25
The other one, we can factorise to:
b. 3x(4-x)
Step-by-step explanation:
For the second option:
Common factor between 12x and 3x^2 is 3x.
Take this out to the front, we are left with:
3x(4-x)
A website I recommend you use (math calculator with some instructions) is Symbolab.
https://www.symbolab.com/solver/factor-calculator/factor%2012x-3x%5E%7B2%7D?or=input