A)=5x5+5x2=25+10=35 sau
=5x7=35
b)8x6-8x3=48-24=24 sau
=8x3=24
c)=2x9+4x9=18+36=54 sau
=6x9=54
d)5x6-3x6=30-18=12 sau
=2x6=12
e)=3x10+2x10+4x10=30+20+40=90 sau
=9x10=90
f)=5x9+1x9+2x9=45+9+18=72 sau
=8x9=72
g)8x7-8x3=56-24=32 sau
=8x4=32
h)=10x4+10x3-10x2=50 sau
=10x5=50