CREATE TABLE table_57094 ("car plates  ( since 1937 ) " TEXT, "Voivodeship Separate city" TEXT, "Capital" TEXT, "Area in 1000km\\u00b2  ( 1930 ) " TEXT, "Population in 1000  ( 1931 ) " TEXT)

between car plates of 80-84 what is the population in 1000 in year 1931?
SELECT "Population in 1000 (1931)" FROM table_57094 WHERE "car plates (since 1937)" = '80-84'
SELECT "Population in 1000 (1931)" FROM "table_57094" WHERE "car plates (since 1937)" = '80-84'