Let’s check each statement individually- Statement I- 30 boys got distinction in final. Here we don’t get any reference about how many girls got distinction. ∴ Statement I alone is not sufficient to find required answer. Statement II- 60% of students got distinction in exam. ∴ 60% of 120 got distinction. ∴ 72 students got distinction. But we don’t know how many girl’s got distinction hence statement II alone is not sufficient to find required answer. Combining both statement, I and II together- 72 students got distinction and amongst them 30 are boys. ∴ 42 girls got distinction. ∴ Both statements together are needed to find the answer.