三个班向灾区捐款,1班捐款钱数是2,3班3/4,2班捐款钱数是1.3班2/5.3班捐款99元,3个班共捐款多少?

三个班向灾区捐款,1班捐款钱数是2,3班3/4,2班捐款钱数是1.3班2/5.3班捐款99元,3个班共捐款多少?
三个班向灾区捐款,1班捐款钱数是2,3班3/4,2班捐款钱数是1.3班2/5.3班捐款99元,3个班共捐款多少?

三个班向灾区捐款,1班捐款钱数是2,3班3/4,2班捐款钱数是1.3班2/5.3班捐款99元,3个班共捐款多少?
设1班捐A,2班捐B,3班捐C,
则A = 3/4(B+C) B=2/5(A+C)
3/4A+A=3/4(A+B+C) 推出A占总的3/7
2/5B+B=2/5(A+B+C) 推出B占总的2/7
所以C即3班占总的2/7 为99元 所以总的为99*7/2=346.5元