1. Chose the way to line up by gender, either BGBGBGBGBG or GBGBGBGBGB. That's 2 ways. 2. For each of these ways we can arrange the boys 5! ways. 3. For each of these ways we can arrange the girls 5! ways. Solution = 2*5!*5! = 2*120*120 = 28800 Edwin