Answer
$d=\frac{301}{10}$
Work Step by Step
$\frac{5}{7}d-\frac{3}{10}=\frac{4}{7}d+4$
$\frac{5}{7}d-\frac{4}{7}d-\frac{3}{10}=4$
$\frac{5}{7}d-\frac{4}{7}d=4+\frac{3}{10}$
$\frac{1}{7}d=\frac{43}{10}$
$d=\frac{43}{10}\times\frac{7}{1}$
$d=\frac{301}{10}$