How do you solve for x in this problem 21=6-1x-4x

You first combine like terms - 1x and - 4x to make the equation 21=6-5x then subtract 6 from itself to cancel it out and from 21, 15=5x where x = 3

Well first you add like terms

21=6-1x-4x

21=6-5x

now, move your x value in front of the =

21=6-5x

-5x - 5x

21-5x=6

next, move the 21 to behind the =

21-5x=6

-21 - 21

-5x=6-21

then do 6-21, which equals - 15, so

-5x=-15

next, divide both sides by - 5

-5x=-15

-5 - 5

x=3