How to solve equation exercises with answers in Grade 6 Hurry up!!!!!!!

How to solve equation exercises with answers in Grade 6 Hurry up!!!!!!!

100x+200=400
100x=400-200
x=200÷100
x=2
50x+100=200
50x=200-100
x=100÷50
x=2
10x+20=40
10x=40-20
x=20÷10
x=2