A)5.(-7)+(-2).(-5)b)5.(-9)+(-2).(-5)c)6.(-5 mū 2)+3.(-15)d)(-57).(67-34)-67.(34-57)e)(-21):3+3.7(-7)g)s=2+(-3)+4(-5)+6+(-7)+....+(-2019)+2020+(-2021)
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