=8.8-

=（8.8-0.8）-

=8-

=6

=

=

=

=（7.8-2.8-1）×0.75，

=4×0.75，

=3；

111×28+999×8，

=111×28+111×72，

=111×（28+72），

=111×100，

=11100，；

=

=

=7；

2

=（2.75+2.25）+（1

=5+5，

=10．