Question 1091443
{{{ 2/7 = 1/2 + Y }}}
I'll go step-by-step.   Subtract 1/2 from each side:
{{{ 2/7 - 1/2 = 1/2 + Y - 1/2 }}}
Simplify right hand side:
{{{ 2/7 - 1/2 = Y }}}    
Rewrite the fractions using a common denominator:
{{{ 4/14 - 7/14 = Y }}}
Simplify:
{{{ -3/14 = Y }}}
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Ans: {{{ highlight( Y = -3/14 ) }}}
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