CREATE TABLE table_name_90 (richmond_ VARCHAR, staten_is VARCHAR, the_bronx VARCHAR)

How many voters were in Manhattan when 181,639 people voted in the Bronx?
SELECT richmond_ AS "staten_is" FROM table_name_90 WHERE the_bronx = "181,639"
SELECT "richmond_" AS "staten_is" FROM "table_name_90" WHERE "181,639" = "the_bronx"