math
posted by TommyBoy .
A farmer had 500 ducks and 300 chickens. He gave his sister 100 chickens and ducks. Later, the farmer bought 10 more ducks and 75 more chickens. As a result, the number of ducks decreased by 12% and the number of chickens increased by 15%.
a) How many ducks did the farmer give away?
b) How many chickens did he give away?

We can do this without algebra:
originally he had 500 ducks
the final number was 12% less , or 88% of the original
= 440 ducks
but that includes the purchase of 10 ducks, so the giveaway must have been 70 ducks
so he must have given away 30 chickens
so his final count for chickens
= 300  30 + 75 (the new purchase) = 345
change = increase of 45 chickens
is this 15% of 300 ? YES
He gave his sister 70 ducks and 30 chickens 
Explain ur answers more