Answer:
b
Step-by-step explanation:
the following equations can be determined from the question
16n + 8o = 336 equation 1
n + o = 30 equation 2
where n = new books
o = old books
Multiply equation 2 by 8
8n + 8o = 240 equation 3
subtract equation 2 from 1
8n = 96
n = 12
substitute for n in equation 2
12 + o = 30
o = 18