There are several classical books on mathematics which are a pleasure to study from. However, after reading its materials and working through the theorems and solved problems, I feel very uncomfortable while solving questions given at the back of the chapter. This happens when they don't have any answers (especially for numerical problems ). How do you handle this problem?
I find teacher's guides are often quite useful for reasons beyond just the answers, though.
In addition, some textbooks have just the answers available under separate cover.
Lastly, try contacting the publisher to see what other classroom resources are available.