How do you combine like terms in ##-4+ 7( 1- 3x )##?

##3 - 21x##

or

##3(1 - 7x)##

First, expand the terms in parenthesis by multiplying each term in the parenthesis by ##7##:

##-4 + (7*1) - (7*3x) ->##

##-4 + 7 - 21x##

Now you can combine like terms, which in this problem is just the constants: ##(-4 + 7) - 21x##

##3 - 21x##

or

##3(1 - 7x)##