Question

How many notebooks can 12 boys and 12 girls complete in 12 weeks? 6 boys can complete writing 6 notebooks in 6 weeks. 4 girls can complete writing 4 notebooks in 4 weeks.

Answer 1

6 boys complete 6 notebook in 6 weeks
so, 6×2=12 notebooks can be completed in 12 weeks by 12 boys. 
Also, 4 girls complete 4 notebook in 4 weeks
so,4×3= 12 notebook can be completed in 12 weeks by 12 girls
total number of notebook by 12 boys and 12 girls = 12+12 =24