3.4+2х=7х-16.1
2х-7х=-16.1-3.4
-5х=-19.5
х=3.9
Б-а=в
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8дм=80см:100=0.8м(1дм=10см)
5,34см:100=0.0534м(1м=100см)
0,23мм:100=0.0023м(1см=10мм)
-1/15*15/8 + 25/6 : 5/3 = - 1/8 + 5/2 = -1/8 + 20/8 = 19/8 = 2 3/8