设鸡有X只,兔有(X-20)/4只.
X+(X-20)/4=100
(X-20)/4=100-X
X-20=4(100-X)
X-20=400-4X
X+4X=400+20
5X=420
X=84
(X-20)/4=(84-20)/4=16只
答:鸡有84只,兔有16只.
设鸡有X只,兔有(X-20)/4只.
X+(X-20)/4=100
(X-20)/4=100-X
X-20=4(100-X)
X-20=400-4X
X+4X=400+20
5X=420
X=84
(X-20)/4=(84-20)/4=16只
答:鸡有84只,兔有16只.