How do you factor #5a - 20 #?
We begin with
There, that's it.
To factor this expression, tell yourself
"I need a number (or variable) that 'go into' both 5a and -20.
Well, 5 is a factor of 5 and -20.
So 5 go into 5a (1a times).
That sounds confusing, but remember, 5 go into 5 one time, but in algebra, you don't normally write the number 1 in coefficient, so it's just 'a'. 5 can't go into 'a' because a is just a single variable.
5 can go into 20, 4 times.
So now our final answer will be 5(a-4).
Hopefully this make sense!