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In the design of a bridge, an engineer determine that four fewer 18-m girders are needed for the span length than 15-m girders. How many 18-m girders are needed?
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by Toan004 at September 17, 2010

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ok so we need x(15)m girds or (x-4)(18) m girds. 15x = 18x - 72, 3x = 72, x = 24

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10531

John_Doe September 17, 2010