怎么简便计算?第一道题7.2×5.8+0.72×42第二道题9.76×0.72-0.76×0.72+0.72第三道题27

0.72*58+0.72*42=0.72*（58+42）=0.72*100=72
0.72*（9.76-0.76+1）=0.72*10=7.2
3.7*（27+75）=3.7*（100+2）=370+7.4=377.4