Brother and sister
A family I know has several has children. Each boy in this family has many sisters as brothers but each girl Has twice as many brothers as sisters. How many brothers and sisters are there? Answer: Since the boys have as many brothers as sisters, there must be 1 boy more than the number of girls. If We try 2 and 1, 3 and 2, and 4 and 3, we will find that 4 boys and 3 girls is the solution to fulfil the requirement that each girl has twice as many brothers as sisters.