10*(920-20)= 8*(720-700)= 184*100-300= 100*391-3000=

10*(920-20)=10*900=90008*(720-700)=8*20=160184*100-300=18400-300=18100100*391-3000=39100-3000=36100

10·(920-20)=10·900=90008·(720-700)=8·20=160184·100-300=18400-300=18100100·391-3000=39100-3000=36100