81.2-11÷7-七分之一×3
=81.2-11÷7-3÷7
=81.2-（11+3）÷7
=81.2-2
=79.2
6696÷62-6.5×10.6
=（6200+496）÷62-13x5.3
=（6200+310+186）÷62-13x5.3
=153-(65+3.9)
=153-69+0.1
=84.1
〔四分之三-（六分之五-三分之二）〕÷四分之五
=(3/4+2/3-5/6)x4/5
=3/5+8/15-2/3
=9/15+8/15-10/15
=7/15