Question 1108478
Notice there are no units mentioned whatsoever.
I am free to assign units and a total amount of
liquid in the container without changing the  problem.
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I will say there are {{{ 24 }}} units of total liquid 
in the container.
{{{ ( 5/12 )*24 = 10 }}} units of the 22.5% water
{{{ ( 7/12 )*24 = 14 }}} units of the 27% water
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{{{ .225*10 = 2.25 }}} units of water in the 22.5% water
{{{ .27*14 = 3.78 }}} units of water in the 27% water
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The FRACTION of water in the container is:
{{{ ( 2.25 + 3.78 ) / 24 = 6.03/24 }}}
{{{ 6.03/24 = .2051 }}}
The PERCENT of water in the container is:
{{{ .2051*100 = 20.51 }}}
20.51%
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check the math & get a 2nd opinion if needed