The first step to factorising this expression, is finding what is common in each term.
The GCF of 3, 2 and -4 is 1 therefore we will not have a coefficient of the outside terms.
Then we have st, su and sv
s is common in all of them therefore we can take out s.
So far we have s( )
Now for each term we must find what we multiply by s to reach it.
3st / s = 3t
2su / s = 2u
-4sv / s = -4v
Now just put these values inside the brackets.
s(3t + 2u - 4v)