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Ответ:
б) 321 + 337 + 363 = 321 + (337 + 363) = 321 + 700 = 1021
в) 234 + 456 + 166 = (234 + 166) + 456 = 400 + 456 = 856
г) 448 + 323 + 52 + 77 = (323 + 77) + (448 + 52) = 400 + 500 = 900
д) 123 +978 + 277 + 22 = (123 + 277) + (978 + 22) = 400 + 1000 = 1400
е) 511 + 245 + 855 + 89 = (511 + 89) + (245 + 855) = 600 + 1100 = 1700
А)-4,8 б)42,12 в)-9,11
г)2 7/9-2 5/6=50/18-51/18=-1/8
д)5,8+х=2,61
х=2,61-5,8
х=-3,19
е)у-4 5/14=5 11/21
у=5 11/21+4 5/14=232/42+183/42
у=415/42=9 37/42
1/9=0,(1)
8/9=0,(8)
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P=2(a+b)
P=30
30=2(a+3)
30=2a+6
2a=30-6
2a=24
a=12
<span>a>12</span>