1) 40 * 50 = 2000 ( cm2)
2) 2 * 2000 = 4000 (cm2)
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3) 40 * 30 = 1200 (см2 )
4) 2 * 1200 = 2400 (cm2)
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5) 50 * 30 = 1500 (cm2)
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6) 4000 + 2400 + 1500 = 7900 (cm2)
7) 7900 cm2 = 0,79 m2
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8) 400 * 0,79 = 316 (руб)
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Ответ 316 рублей