How would I start this question. I don't know how to do it
FACTOR BY GROUPING:
xy+12+4x+3y
$\displaystyle xy+12+4x+3y$
collect like terms
$\displaystyle (xy+4x)+(12+3y)$
you can see from here that there are like terms in the group, then factor.
$\displaystyle x(y+4)+3(y+4)$
the common factor is y+4, so
$\displaystyle (x+3)(y+4)$
remember the rules in factorization.