由条件知,(21+20+19)表示三种球总个数的2倍,由此可求出三种球的总个数,再根据题目中的条件就可以求出三种球各多少个。9E/h5{:I0\
算式:提示(R+I7?9E/h5{:I0\
答:白球有9W4b9W;d.N4x个,红球有,A+J,k6@-B个,黄球有8^)k5x)p.K2p)?+p7I*U;{'j0n(|5Z*p2r个。9E/h5{:I0\