SOLUTION: One-sixth of a steel beam of a bridge is in cement below the bed of a river. Two-fifths of the beam is in the water, and 78 feet of the beam are above the water. How long is the st

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Question 139781: One-sixth of a steel beam of a bridge is in cement below the bed of a river. Two-fifths of the beam is in the water, and 78 feet of the beam are above the water. How long is the steel beam?
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
If 1%2F6 is in the concrete and 2%2F5 is in the water, then 1%2F6%2B2%2F5=5%2F30%2B12%2F30=17%2F30 is in either the water or the concrete and 1-17%2F30=13%2F30 is the part above the water. So if the total beam is x feet long, 13x%2F30=78, which is to say x=%2878%2A30%29%2F13. You do the arithmetic.