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Verified answer

1416.

(13,4 - у) * 4,3 - 20,05 = 78,05 + 6,7у,
57,62 - 4,3у - 20,05 = 78,05 + 6,7у,
11у = -40,48,
у = -3,68,

(16,2 - х) * 3,2 - 50,08 = -8,12 - 5,1х,
51,84 - 3,2х - 50,08 = -8,12 - 5,1х,
1,9х = -9,88,
х = -5,2,



816.

70 кг карт.  ----  14 кг крахм.,  ?%,

(14 : 70) * 100% = 1/5 * 100% = 20%,


819.

222 1/25 : (131 - 128 2/5) + 46 1/2 : 3/10 = 238 2/5,

1) 131 - 128 2/5 = 130 5/5 - 128 2/5 = 2 3/5,
2) 222 1/25 : 2 3/5 = 5551/25 : 13/5 = 5551/25 * 5/13 = 427/5 = 85 2/5,
3) 46 1/2 : 3/10 = 93/2 * 10/3 = 5 * 31 = 155,
4) 85 2/5 + 155 = 240 2/5