弱弱的问一题数学题--代数

nicchasedream

来自与陈向东的 GMAT数学:
19 例题:　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). On a day when the temperatures extremes recorded at a certain weather station differed by 45 degrees on the Fahrenheit scale, by how many degrees did the temperature extermes differ on the Celsius scale?
答案是 25

就算看了解释也不明白为什么会将(F-32) 省略考虑而直接 算出来。。。。脑子突然卡住了。。。。请知道的童鞋点醒一下

sdcar2010

The ratio of change in C vs. F is 5:9.

nicchasedream

oh thank you ....finally i get it...lack of basic knowledge between Celsius and Fahrenheit ...