Suppose that in a certain triangle, the degree measures of the exterior angles are in the ratio $2:3:4$. If the largest interior angle measures $y^\circ$, what is the value of $y$?
The exterior angles sum to 360o, so if the "unit" exterior angle is x then 2x + 3x + 4x = 360 or x = 40o. The smallest exterior angle is 2x = 80o. So the largest interior angle is 180o - 80o = 100o.
