Question

The number of rooms on the ground floor of a building is $12$ less twice the number of room on the first floor. If the first floor has $x$ rooms, how many rooms are there on the ground floor.

Answer 1

The number on first floor are $x$ rooms.
Twice the number of rooms on first floor can be written as:
$=2x$
$12$ less twice the number of room on the first floor can be written as:
$=2x-12$
But,
the number of rooms on ground floor is equal to $12$ less twice the number of room on the first floor.
Hence the number of rooms on ground floor can be written as:
$=2x-12$