А. 1)396га(3960000кв.м.) :1800=2200м-длина поля. 2)(1800+2200)*2=8000м(8км)-периметр поля. Б. 1)8дм*3дм*12дм=288дм3-размер бруска. 2)288*2600=748800г(748кг800г)-масса бруска.
43/45 - 20/25 = 43/45 - 4/5 = 43/45 - 36/45 = 7/45
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((32/57 + 27/38) * 19/29 + (25/26 + 48/65) * 10/51 + (74/75 + 49/50) * 15/59) * 3/5 =
= ((145/114) * 19/29 + (25/26 + 48/65) * 10/51 + (74/75 + 49/50) * 15/59) * 3/5 =
= ((145/114) * 19/29 + (17/10) * 10/51 + (74/75 + 49/50) * 15/59) * 3/5 =
= ((145/114) * 19/29 + (17/10) * 10/51 + (59/30) * 15/59) * 3/5 =
= (5/6 + (17/10) * 10/51 + (59/30) * 15/59) * 3/5 =
= (5/6 + 1/3 + (59/30) * 15/59) * 3/5 = (5/6 + 1/3 + 1/2) * 3/5 =
= (5/3) * 3/5 = 1
0,6x=1,392÷1,6÷1
0,6x=1,392÷1,6
0,6x=0,87
умножить обе части на 100:
60x=87
x=87/60
x=29/20 => x=1,45