Lets start with A

Veg- 2:3 ( s:ns)
Non Veg- 4:3 ( s:ns)

If this is actual condition that we have 3 nv ns who can eat hamburgers out of total 12(2+3+4+3). Now we have 15 hamburger so lets multiply this by 5
So total guest=12*5=60- suff

B- 30% veg non students that means 20 % veg students because half of the guests were veg.

15 hamburgers -15 non veg non student- no info about non veg student- insuff

Ans: A

hemant why u've added all 4 numbers.....
please explain why 12 and how??

Let assume that ratio given is the actual number so in that case ppl who would be able to eat hamburger would be

nsnv out of (nsnv+snv+snv+sv)

so 3 of 12..now this will account for 3 hamburger we need 15 so multiply by 5 to keep the same ratio

3*5 of 12*5