help : two old jijings...

redhat

1. A boy walkig along a road at 3 kilometers per hour is overtaken by a truck traveling at 40 kilometer per hour.  If the truck breaks down 1 kilometer beyoud where it passes the boy, how many minutes agter the breakdown does the boy reach the truck?

ANS. 18.5 mins

2.If C is the temperature in degrees Celsius and F is the temperature on the two scales is expressed by the equation 9C=5(F-32).  On a day when the temperature extremes recorded at a certain weather station differed by 45 degrees on the Fahrenheit scale, by how many degrees did the temperature extremes differ on the Celsius scale?

ANS. 25

Thanks a lot.



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tongxun

1、走1mile，花时间1/40 小时
在这个时间内，人走了3/40 mile，
实际的距离应该是：1- 3/40 mile
[（1-3/40）/3] *60 =18.5min
2、9c=5f -160
9c1=5(f1-45)-160
9c1=5f1-160-225
9c1+225=9c
  c1+25=c

redhat

这个地方不太瞭:

9c1+225=9c
c1+25=c

tongxun

因为9C=5(F-32)，所以5f1-160=9c1
9c1=5f1-160-225  =>9c1+225=9c