My suggestion is to look on google, there are plenty of answers and I think it will explain better than me.
To factor a polynomial we need to find 2 numbers that add up to -15 and multiply into -54.
(-x -18)(x +3) Will be your answer.
Answer:
3x(x-1)-5(x-1)
=3x²-3x-5x+5 (we can count it one by one)
=3x²-8x+5 (we can calculate the same variable)
#i'm from indonesia
hope it helps.