If C is the temperature in degrees Celsins and F is the temperature in degrees Fahrenheit, then the relationship between temperatures on the two scales is expressed by the equation 9C=5(F-32). The temperature to boil water at sea level altitude and to boil on top of Mt. Everest differed by 15 degrees on the Fahrenheit scale, by how many degrees did the temperature extremes differ on the Celsius scale?
Options:
(A) a)  65/9
(B) b) 7
(C) c)  25
(D) d)  45
(E) e)  81 Think first, then make a decision. Some random thoughts:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The relationship is 9/5 - 32, so approximately half of difference in Celsius (the -32 part won't be used in this case). Just looking at the answer choices you can pick B which is the only number near half of 15. The other answer choices are too far apart so no need to calculate. So the answer is (B).