Example 5. If $A=20^{\circ}, B=25^{\circ}$, find $(1+\operatorname{tg} A)$
- $(1+\operatorname{tg} B)$.

 untranslated part: 
- $(1+\operatorname{tg} B)$ 的值.

Note: The untranslated part is kept as is because "tg" is a notation for the tangent function, and the phrase "的值" means "the value of" in this context. However, for a complete translation, it should read: 
- the value of $(1+\operatorname{tg} B)$. 

Thus, the fully translated text is:

Example 5. If $A=20^{\circ}, B=25^{\circ}$, find the value of $(1+\operatorname{tg} A)$
- $(1+\operatorname{tg} B)$.