Q: 7 boys, 3 are identical clones. 7 girls, 2 are clones. one of the non-clone boy is Kevin, how many ways can Kevin sit in a row so he is not next to a non-clone girl ?
My A: total - (Kevin sits with a non-clone girl). = total - (Kevin has non-clone girl in the left + Kevin has non-clone girl in the right - both sides of Kevin are non-clone girls). (updated based on comment)
But my answer is different from others. What's the correct answer pls ?