Araba and Ama share 20 oranges in such a way that Araba receives 12 oranges. To find the ratio of Araba's share to that of Ama, you can divide the number of oranges Araba received by the number of oranges Ama received:
Ratio = Araba's share / Ama's share
Ratio = 12 oranges / (20 - 12) oranges
Ratio = 12 oranges / 8 oranges
Ratio = 3/2
So, the ratio of Araba's share to that of Ama is 3:2.