Okay, let's break this down step-by-step: * 90% of 90 girls showed up on time * 90% is 0.9 * 0.9 * 90 is 81 girls on time * The total number of girls is 90 * So the number of girls late is 90 - 81 = 9 * 80% of 110 boys showed up on time * 80% is 0.8 * 0.8 * 110 is 88 boys on time * The total number of boys is 110 * So the number of boys late is 110 - 88 = 22 * The total number of children late is the girls (9) + the boys (22) * So the total number