Take the amount of rows in the auditorium, 15, and multiply that by the number of new seats in each row, 3. You get 45. Now multiply the number of new seats, 45, by the cost of each seat, $74. You get $3,330.
An exterior angle of a triangle is equal to the sum of the two opposite interior angles. Example : Find the values of x and y in the following triangle. y + 92° = 180° (interior angle + adjacent exterior angle = 180°.)