CREATE TABLE table_51015 ("Constituency" TEXT, "Electorate" FLOAT, "Votes" FLOAT, "Turnout" FLOAT, "Spoilt" FLOAT, "Percent Yes" FLOAT)

WHAT IS AN AVERAGE ELECTORATE WITH VOTES OF 28,475 AND SPOILT SMALLER THAN 5,779?
SELECT AVG("Electorate") FROM table_51015 WHERE "Votes" = '28,475' AND "Spoilt" < '5,779'
SELECT AVG("Electorate") FROM "table_51015" WHERE "Spoilt" < '5,779' AND "Votes" = '28,475'