Total number of balls = 100
Number of balls with odd numbers = 50
Number of balls with number greater than 80 = 20
Number of balls greater than 80 and is odd = 10
⇒ Number of favourable outcomes = 50 + 20 - 10 = 60
P(odd or greater than 80) = 60/100 = 3/5
Answer: 3/5