One plane can travel 20 miles per hour faster than another. One of them goes 285 miles in the same time it takes the other to go 255 miles. What are their speeds?

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Answer 1 · 2017-07-31T13:02:45

190 miles/hr and 170 miles/hr

Let the speed of faster plane be x
Therefore speed of slower plane=x-20

As the time taken is the same,

#285/x=255/(x-20)#

#rArr 57/x=51/(x-20)#

#rArr 57(x-20)=51x#

#rArr 57x-1140=51x#

#rArr 6x=1140#

#rArr x=190#

Therefore faster plane travels at #190 " miles"*hr^(-1)#
Speed of slower plane= x-20

= 190-20

=170 miles/hr