We line up the tens place of 33 and 42 as well as the ones place so that it looks like:
33
+42
--------
Then we add first the ones, which is 3 + 2 for 5. Then we add the tens together, 3 + 4 is 7. We put the five first since its in the ones place and the 7 second since its in the tens place for 75.
