Correct Answer - Option 1 : 60

**Given:**

% of students who were absent in the class = 15%

Number of present students = 51

Formula used:

The formula of percentage.

X% of Y = XY/100

Calculation:

Let total number of students = x

Number of absent students = 15x/100

⇒ 3x/20

So, number of present students = x - 3x/20

⇒ 17x/20

17x/20 = 51

⇒ x = 60

∴ The total number of students is 60