Remark
Set up a proportion.
Solution
30/36 = x/758 Cross multiply
758 * 30 = 36 * x combine the numbers on the left
22740 = 36x Divide by 36 on both sides
22740/ 36 = 36/36 x Combine the left
631.6667 = x Switch
x = 631.66667 The answer depends on what you have been told about rounding. My own feeling is that you round down. You haven't got, nor can you get, 2/3 of a person. Others may say to round up. Then the answer is 632 to the nearest person. Your question says about how many students went hiking. To me 631 is closer to what the definition of about is.
Answer: 631 but don't be surprised if about means 632.