I don’t know if that’s what you wanted but I hope I helped ;D (sorry for my bad english)
Answer:
It will take a total of twenty minutes
Step-by-step explanation:
if it cools from 200 to 195 in five minutes then times two is twenty which means it's cooled to 190.
180 is twenty less then 200 so if it takes ten minutes to cool down by ten then multiply this by two and you get 180 and know it's cooled by twenty minutes
The first book was $6. The second book was $10. The last book was $20.
Hope this helps!