3.5X7.7+1.23X35
=3.5X7.7+1.23X3.5X10
=3.5X7.7+12.3X3.5
=3.5X(7.7+12.3)
=3.5X20
=70
9.9X20.2
=(10-0.1)X20.2
=10X20.2-0.1X20.2
=202-2.02
=199.8
3.5X7.7+1.23X35
=3.5X7.7+1.23X3.5X10
=3.5X7.7+12.3X3.5
=3.5X(7.7+12.3)
=3.5X20
=70
9.9X20.2
=(10-0.1)X20.2
=10X20.2-0.1X20.2
=202-2.02
=199.8