### Instruction: the c . p of 20 books is equal to the s . p of 30 books . find his gain % or loss % ? Let's write a Python program.### Response: n0 = 20.0
n1 = 30.0
t0 = n0 / n1
t1 = 1.0 - t0
answer = t1 * 100.0
print(answer)