-20+4x = -6x
4x + 6x =20 (in here i put the like terms in one place.so it can be easy to calculate and when changing the terms the sign will be also change)
10x =20 ( in this process i add like terms)
x = 20/10 ( here 10x is multiplication so we can break the terms and change multiplication into division while putting 10 in right hand side. as i said earlier while changing terms the sign will be also change.
x = 2 ( here i divided 10 and 20 so i can get the answer)
so the ans is x = 2
