Answer:
When solving equations the goal is to get the variable by itself so
4.5+1.5k=18-3k (first step is to subtract 4.5 from each side)
1.5k=13.5-3k (4.5-4.5=0, 18-4.5=13.5) (Next is to add 3k to each side)
4.5k=13.5 (1.5k+3k=4.5k, -3k+3k=0) (Last you divide both sides by 4.5)
k=3 (4.5/4.5=1, 13.5/4.5=3)
k=3
Hope this helps ;)