In forestry of 100 new allotments. Pines zasazhena1/5chast all allotments, and other allotments are set with fir-trees. How many allotments are set with fir-trees? Help to solve please conditions

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Since 1/5 part are set with pines, fir-trees set 5/5-1/5=4/5. 1/5 part from hundred - 100/5*1=20, 20 allotments are set with pines, and fir-trees 100-20=801/5=5. 1) 100/5=20 (affairs.) - it is set with pines. 2) 100-20=80 (affairs.) - it is set with fir-trees. Answer: 80 allotments.
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