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Question Number 195661 by otchereabdullai@gmail.com last updated on 06/Aug/23

Commented by otchereabdullai@gmail.com last updated on 07/Aug/23

thanks prof

thanksprof

Commented by mr W last updated on 07/Aug/23

even when the whole road is good, he  needs ((23)/(52))×60=26.5 minutes. that  means he can never drive 23 km in  only 25 minutes.  ⇒question is wrong!

evenwhenthewholeroadisgood,heneeds2352×60=26.5minutes.thatmeanshecanneverdrive23kminonly25minutes.questioniswrong!

Answered by som(math1967) last updated on 07/Aug/23

 let good road=xkm  ∴ bad road=23−x   (x/(52)) +(((23−x))/(28))=((25)/(60))  ⇒ ((7x+13(23−x))/(4×13×7))=(5/(12))  ⇒−6x+13×23=((5×13×7)/3)  ⇒ 18x=13×23×3−35×13  ⇒x=((13(69−35))/(18))=((13×17)/9)=24.5km   24.5>23 ?    length of good road>total length  ?

letgoodroad=xkmbadroad=23xx52+(23x)28=25607x+13(23x)4×13×7=5126x+13×23=5×13×7318x=13×23×335×13x=13(6935)18=13×179=24.5km24.5>23?lengthofgoodroad>totallength?

Commented by otchereabdullai@gmail.com last updated on 07/Aug/23

thanks sir

thankssir

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