Page 25 of the sixth grade of the mathematics experimental class Three classes of the sixth grade of a school held a donation activity, and the three classes donated 2 10 yuan.
2/3 of Class B and C Party A, then 2/5 of Party A's total investment.
Category B is 2/5 of the sum of A and C, and then 2/7 of the total donation.
C: 2 10×( 1-2/5-2/7)
=2 10× 1 1/35
=66 yuan