Question: When itogon, benguet is the city/municipality and 1st class is the income classification how many measurements of population in 2010?
Schema: create table table_29289372_1 (population__2010_ varchar, income_classification varchar, city_municipality varchar, PRIMARY KEY (population__2010_))
SQL: select count(population__2010_) from table_29289372_1 where income_classification = "1st class" and city_municipality = "itogon, benguet"