11. A, B, and C together have 100 yuan. If A's money becomes 6 times the original, B's money becomes $1 / 3$ of the original, and C's money remains unchanged, then the three of them still have a total of 100 yuan. C's money does not exceed 30 yuan. Question: How much money do A, B, and C each have?
11. $x, y, z$ represent the amounts of money that A, B, and C have, respectively. $x+y+z=100, 18x+y+3z=300$. $x=10-2t, y=75-15t, z=15+17t, t=0,1, \cdots, 5. t=0$ gives the required solution.