Answer
$\frac{-1+\sqrt 7}{4}\approx0.4$
Work Step by Step
Multiply both sides by the denominator of the left side.
$\frac{x}{2+\sqrt 7}=\frac{3-\sqrt 7}{4}$
$x=\frac{(3-\sqrt 7)(2+\sqrt 7)}{4}=$
$\frac{6+3\sqrt 7-2\sqrt 7-7}{4}=$
$\frac{-1+\sqrt 7}{4}\approx0.4$
