In addition to four dogs Eldon White has four children. The youngest Betsy is nine years old, then there are twins Arthur and Robert and finally there is Laura the eldest whose age is equal to the combined ages of Betsy and Robert. Also the combined ages of the twins are the same as the combined ages of the youngest and eldest. How old is each children?
If the eldest is 9 years older than the twins, and the age of the twins is the average of the age of the oldest and youngest, then the youngest must be 9 years younger than the twins.
