6. (10 points) Person A and Person B work together on a project, which can be completed in several days. If Person A completes half of the project alone, it will take 10 days less than if Person A and Person B work together to complete the entire project; if Person B completes half of the project alone, it will take 15 days more than if Person A and Person B work together to complete the entire project. How many days will it take for Person A and Person B to complete the entire project together? $\qquad$ days.
【Solution】Solution: Let's assume that it takes $x$ days for person A and person B to complete the entire project together, then person A alone needs $x-10$ days to complete half of the project, and person B alone needs $x+15$ days to complete half of the project. Person A alone needs $2(x-10)$ days to complete the entire project, and person B alone needs $2(x+15)$ days to complete the entire project. Therefore, $\frac{1}{2(x-10)}+\frac{1}{2(x+15)}=\frac{1}{x}$, solving this equation yields $x=60$. Therefore, the answer is 60.