The exterior angles need to equal 360 degrees.
You have 100 + 110 + 130 = 340
So 3x + 5x need to equal 360 - 340 = 20
8x = 20
x = 20 /8 = 2.5
3x = 3 *2.5 = 7.5
5x = 5 * 2.5 = 12.5
An interior angle and an exterior angle need to equal 180 degrees.
The largest interior angle would need to correspond with the smallest exterior angle.
The smallest exterior angle is 3x which equals 7.5 degrees.
The largest interior angle would be 180 - 7.5 = 172.5 degrees.