а)11/12*3 3/7:11/21-(1/36-2 7/15):1 2/5=11/21*3 3/7:11/21-2 79/180:1 2/5= 3 1/7:11/21-2 79/180:1 2/5=6-1 187/252=4 65/252
б) 51-(86,45:24,7+1,25)*2,4-36,99=51-(3,5+1,25)*2,4-36,99=51-4,75*2,4-36,99=51-11,4-36,99=39,6-36,99=2,61
УРАВНЕНИЕ:
(у-15,7):5,14+11/3=6 1/3
5,14у-80,698:5,14+11/3=6 1/3
5,14у-15,7+11/3=6 1/3
5,14у=6 1/3+15,7-11/3
5,14у=18,36
у=18,36:5,14
у=3,57
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5,14*3,57=18,36