1 here are some red,white and black balls.the sum of the whi

1 here are some red,white and black balls.the sum of the white and red balls is 10,and the sum of the red and black ones is 7,the black and the white ones is 5.how many balls of each colour?
2 a farmer has bought 123 chicks and 86 ducks .the total cost of chicks and ducks is 504 yuan.and we know the price of 3 chicks equals that of 2ducks.what's the price of each chick and duck?
3 a rope is cut off 4 times ,and each time a half part of the left is cut off,when the cutting comes to the 4th time,the length of the part left is 2 meters.how many meters is the rope?