Addition and subtraction expression

#1
rule : r - 12

Missing number = 25 (37-12 = 25)

#2
rule: a + 34
Missing number = 43 (9+34 = 43)

#3
rule: s - 5
Missing number = 20 (25-5 = 20)

#4
rule: b+16

Missing number = 0 (0+16= 16)

#5
rule: w+3

Missing number = 9 (6+3= 9)

#6
rule: n-11

Missing number = 22 (33-11= 22)

#7
15 - n when n = 9
15 - 9 =6

#8
32 more than a number d:
 
32 +d
answer is C. 32+d

#9
Variable is an unknown value. So you need to solve that unknown value in the problem.

i would say 18

Step-by-step explanation:

out of the letters you gave us only 5 groups out of 25 had 2 freshmen in them if it continues then for each 25 groups 5 will have 2 freshmen so at 50 its 10 at 100 its 15 and at 115 it would be about 18