\(\eqalign{
& {x^2} + 4x = x\left( {x + 4} \right) \cr
& 2x + 8 = 2\left( {x + 4} \right) \cr
& \Rightarrow MTC = 2x\left( {x + 4} \right) \cr} \)
\(\eqalign{& {6 \over {{x^2} + 4x}} + {3 \over {2x + 8}}\cr& = {6 \over {x\left( {x + 4} \right)}} + {3 \over {2\left( {x + 4} \right)}} \cr & = {{6.2} \over {2x(x + 4)}} + {{3x} \over {2x(x + 4)}} \cr & = {{12 + 3x} \over {2x(x + 4)}} = {{3(x + 4)} \over {2x(x + 4)}} = {3 \over {2x}} \cr} \)