24x5÷24x5
=24÷24x5 x5
=1x5x5
=25
125x(8x4)x5
=(125x8)x(4x5)
=1000x20
=20000
25x99
=25x(100-1)
=25x100-25
=2500-25
=2475
75x4x2x5
=(75x4)x(2x5)
=300x10
=3000
99x78
=(100-1)x78
=7800-78
=7722
45+45x26+45x75
=45x2+45(25+75)
=90+45x100
=90+4500
=4590
24x5+24x5
=23x(5+5)
=24x10
=240
25x(26x4)
=25x4x26
=100x26
=2600