Saturday, October 2, 2010

For Kai Zheng

Let the number of cows = x.
If we have 160 more cows than sheep, then the number of sheep is x - 160.

After selling off 25% of the cows, the farmer is left with 75% of the cows. So the number of cows left after the fair will be 75% multiple with x.

After selling 2 fifth of the sheeps, the farmer is left with 3 fifth of the sheeps. So the number of sheeps left after the fair will be 3/5 multiple with (x - 160).

If after the fair the farmer still has 156 more cows then sheeps, then the following equation can be built.
x times 75% = (3/5 times (x - 160)) + 156

By changing 75% into 3/4 you will get x = 400.

Therefore the farmer has 400 cows in the beginning.

Hope this is clear.

No comments:

Post a Comment