56.8×35.7+56.8×28.5+64.2×43.2，
=56.8×（35.7+28.5）+64.2×43.2，
=56.8×64.2+64.2×43.2，
=（56.8+43.2）×64.2，
=100×64.2，
=6420．
故答案为：6420．