Thực hiện các phép tính sau: 2(5/7).4(1/5)

a)257.415=197.215=575.b)658:274=538:154=5330

c)678.−2149=558.−329=−2209

d)178:−414=158:−174=−1534

e)−429.−512=−389.−112=2099f)−289:−413=−269:−133=2639g)365.2=3+65.2=3.2+65.2=6+125=425h)547:2=5+47:2=52+27=3914