28x35+72x72=28x35+72x（35+37）=28x35+35x72+72x37=35x（28+72）+2664=3500+2664=6164供参考。
原式=14×70+72×70+72×2=（14+72）×70+144=86×70+144=6020+144=6164.
28x35+72x72=28x35+72x35+72x35+72x2=35x(28+72+72)+144=6164
