I'm a Chinese student and just wonder why you have interests in Chinese math and science texts.Do you just want to learn mandarin.Actually,I would like to read texts written in English rather than in Chinese.Many Chinese math and science books are not good,though there are some well-written.
I agree that go back to the definition of odd and even function will be helpful.
f(x)=-f(-x) and g(x)=g(-x),so f(-a)=-b, g(-c)=g(c)=b
Now,I'm sure you know how to solve it