Question

After covering 3/4 of his journey, Shrawan realised that he had to go another 15/2 reach his destination.
i. How long was his journey?
ii. What distance has he covered?
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Answer 1

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i) 30 km

ii) 22.5 m

Answer 2

We have 

n2−nC2=n2−nC10

We know that

nCx=nCy⇒x=y or x+y=n

⇒2+10=n2−n

⇒n2−n=12

⇒n2−n−12=0

⇒n2−4n+3n−12

⇒n(n−4)+3(n−4)=0

⇒(n+3)(n−4)=0

⇒n=4, −3

So, n=4  [n is non negative integer]