Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_28180840_15 ( semifinal__week_ VARCHAR, age_s_ VARCHAR )

### Question ###
How many performers are 29 that made it to the semi finals?

### Accurate SQL ###

SELECT semifinal__week_ FROM table_28180840_15 WHERE age_s_ = "29"