36×56+72x73−72=36×2×28+72x73−72=72×28+72x73−72=72×（28+73−1）=72×100=7200
简单方法是运用分配律计算，36×2×28+72×73-72=72×(28+73-1)=72×100=7200，得到答案为7200
