document.write( "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? \n" ); document.write( "

Algebra.Com's Answer #101888 by solver91311(24713) $\"\"$ $\"About$

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. \n" ); document.write( "

\n" );