so, start floor = x
x + 7 - 9 - 4 + 8 - 2 = 14
x = 14
the elevator started on the 14th floor.
to verify: 14 + 7 = 21 - 9 = 12 - 4 = 8 + 8 = 16 - 2 = 14
For this case we must simplify the following expression:

We solve the operation of the second parenthesis, taking into account that different signs are subtracted and the sign of the major is placed:

We multiply:

We eliminate the parentheses:

We add similar terms, taking into account that equal signs are added and the same sign is placed:

Answer:
The simplified expression is: 
The percent would be 29%. You need to move the decimal to the right twice.