Question 31103
Let weight of full grown giraffe = g 
Let weight of full grown lion    = l 
Let weight of full grown chettah = c

According to first condition i.e. full-grown giraffe is about 6 times heavier than a full grown lion.... we get the equation  

g = 6l.................(1)

According to second condition i.e. A full grown cheetah is about one quarter as heavy as a full grown lion.... we get the equation  

c = l/4.................(2)

According to third condition i.e. Together, they are about 450kg.... we get the equation  ..

g + c + l = 450kg

Putting the values of g and c from (1) and (2)...we get 

6l + l/4 + l = 450

solving the LHS and taking the LCM would give us ...

29l/4 = 450

on cross multipication we get ....

29l = 1800

l = 62 kg apporoximately..

Now put the value of l in (1) and (2) we get..

g = 6l

 = 6 * 62

 = 372kg

c = l/4 

  = 62/4

  = 16 kg appoximately..

therefore lion = 62kg ,,,,giraffe = 372kg and chettah = 16kg...and to verify ,,,if we add their weight adds upto 450kg,,,, which is our third condition in the question...