On poultry farm to factory grow up hens, ducks and turkey-cocks, quantity of ducks 0.42 from all birds, turkey-cocks-9/28 from ducks How many birds on this poultry farm if turkey-cocks 54?

Let's go since the end. Turkey-cocks - 54. These are 9/28 ducks. That is to find the modem how many ducks: 54÷9=6 ducks are the share of 1 part. Parts such 28 (9/28): 6×28=168 - ducks Quantity of ducks-0.42 of all birds, that is 42. Therefore: 168/42×100=400 birds only. Answer: 400
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