the numenator of a fraction is …

Assume denominator = x then, numerator =  x - 1
{tex}\therefore{/tex} Fraction = {tex}\frac{x - 1}{x}{/tex}
According  to given situation, we have 

{tex}\frac{x - 1 + 3}{x + 3}{/tex} = {tex}\frac{x - 1}{x}{/tex} + {tex}\frac{3}{28}{/tex}
{tex}\Rightarrow{/tex}{tex}\frac{x + 2}{x + 3}{/tex} - {tex}\frac{x - 1}{x}{/tex} = {tex}\frac{3}{28}{/tex}
{tex}\Rightarrow{/tex}{tex}\frac { ( x + 2 ) x - ( x - 1 ) ( x + 3 ) } { ( x + 3 ) x }{/tex} = {tex}\frac{3}{28}{/tex}
{tex}\Rightarrow{/tex}{tex}\frac { x ^ { 2 } + 2 x - \left( x ^ { 2 } + 2 x - 3 \right) } { x ^ { 2 } + 3 x }{/tex} = {tex}\frac{3}{28}{/tex}
{tex}\Rightarrow{/tex}3{tex}\times{/tex}28 = 3(x² + 3x)
{tex}\Rightarrow{/tex}x² + 3x - 28 = 0

Factorize the above quadratic equation, we get
{tex}\Rightarrow{/tex}(x + 7)(x - 4) = 0 {tex}\Rightarrow{/tex}x = -7 or x = 4
Rejecting x = -7 {tex}\therefore{/tex}x = 4
{tex}\therefore{/tex} Fraction is {tex}\frac{4 - 1}{4}{/tex} = {tex}\frac{3}{4}{/tex}