The easiest way I find of answering questions like these are to start with the numbers on the right and work left
So to answer 222+203 I would first do
2+3=5
Then
20+00=20
I would then add those two numbers up
20+5=25
I would then do
200+200=400
And to finish off I would do
400+25=425
I find this method the easiest for working out a question like this.
I hope this has helped you.