=(40 1- 1))25

= 10000

2、(8 12-56× 12)/28

=(8 12-672)/28

= 140/28

=5

3、99× 124

=( 100- 1)× 124

= 100× 124 - 1× 124

= 12400- 124

= 12276

4、(750+250/5)/8

=(750+50)/8

=800/8

= 100