There are six rows with 18 chairs in each row. In the center of those chairs for rows of six chairs are brown. The rest of the chairs are blue. How many chairs are blue?

IN each row the 6 chairs in the middle are brown. That means 1/3 of t he chairs are brown in each row, therefore 1/3 of the chairs in total are brown. That means 2/3 of the chairs are blue, therefore 18*6*2/3 = 216/3 = 72 chairs are blue