ssandeepan wrote:

IMO C

Let distance be S ;

so , bob cycled S/2 => S/2= x*t1 ( t1= time taken to cycle ) => t1=S/2x

and S/2 = y*t2 ( t2 is time taken to walk ) => t2 = S/2y

now t1 + t2 = t

=> S/2x + S/2y= t => S* ( x+y)/2xy = t=> S= 2xyt/( x+y)

I don't get this question.

Normally I just use the pick-a-number-approach.

If we choose for d (distance): 10 miles, for x 10 and for y 5.

t would be 90 minutes or 1,5 hours.

If I try this for answer choice A it fits.

Can anyone explain what I am doing wrong?

Many thanks.