goi 3 so do la a,b,c
theo dau bai ta co
a/3=b/5=c/7 va a+b+c = 230
ap dung tinh chat day ti so bang nhau ta co
a/3=b/5=c/7= a+b+c/ 3+5+7= 230/15= 46/3
==> a/3= 46/3 ==> a= 46
=> b/5= 46/3=>b= 23//3
==>c/7=46/3=> c= 322/3
vay 3 phan lan luot la.................