Question 52517
I don't know the "proper" way to solve that... but I would just solve it by saying:


9 + 9 + 9 = 27


9 - 2 = 7


9 + 2 = 11


therefore, 7 + 9 + 11 = 27 which is between 20 and 30


7 + 7 + 7 =  21


7 - 2 = 5


7 + 2 = 9


therefore, 5 + 7 + 9 = 21 which is between 20 and 30


making the answers 5,7,9 and 7,9,11