(b) 80o
Let the measures of the given angles be (2x)o, (3x)o and (4x)o.
(2x)o + (3x)o + (4x)o = 180o
⇒ (9x)o = 180o
⇒ x = 180 / 9
⇒ x = 20o
2x = 40o, 3x = 60o, 4x = 80o
Hence, the measures of the angles of the triangle are 40o, 60o, 80o.
Thus, the largest angle is 80o.