Table: southern_locomotives_3
Columns: class
wheels
date
no_built
loco_nos
comments

Question: Which class at 55 built?
SQL: SELECT "class" FROM southern_locomotives_3 WHERE "no_built" = 55

Question: What is the Loco Nos of the e3 class?
SQL: SELECT "loco_nos" FROM southern_locomotives_3 WHERE "class" = 'e3'