Question 1053954
Let {{{ a }}} = amount given to eldest son
Let {{{ b }}} = amount given to youngest son
Let {{{ c }}} = amount given to daughter
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given:
{{{ a/c = 2/1 }}}
{{{ b/c = 5/3 }}}
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{{{ (( a/c )) / (( b/c )) = a/b }}}
{{{ (( 2/1 )) / (( 5/3 )) = ( 2/1 )*( 3/5 ) = 6/5 }}}
The ratio of the amount given to the eldest son 
to the amount given to the youngest son is 6/5