Hi, Michael.
Okay, so if there are 641 boys and 490 girls, then there are 1,131 total children.
If each child makes 8 art pieces, then:
1131 x 8 = 9048
There are 9,048 total pieces.
If they are distributed among 58 classrooms:
9048 ÷ 58 = 156
There are 156 pieces in each classroom.