On june 17 the temperate in new york city ranged from ...?

Question

90 to 99 while the temperature in Niagra falls ranged from 60 to 69. the difference in the temperatures in these two cities must be between....

20 and 30 20 and 40 25 and 35 30 and 40

i cant figure out the answer to this question please help

Answer 1

Another way of asking this question would be to ask:

If the temperature in NYC is between 90-99, and the temperature in Niagra falls is between 60-69...what is the maximum possible difference between temperatures and the minimum possible difference between temperatures at these two cities.

So what temperatures at the two cities would provide the smallest difference, and what two temperatures would provide the largest difference?