Answer :
[tex]\frac{1}{5}d+\frac{1}{8}d=2\\\\
Make\ common\ denominator\ of\ \frac{1}{5}\ and\ \frac{1}{8}\ which\ is\ 40:\\\\
\frac{8}{40}d+\frac{5}{40}d=2\ \ \ |*40\\\\8d+5d=2*40\\\\
13d=80\ \ |:13\\\\d=\frac{80}{13}=6\frac{2}{13}\\\\
Answer\ is\ d=6\frac{2}{13}.[/tex]
I thought you're saying that the denominators are 5d and 8d.
If so, then the common denominator is 40d, and 'd' turns out to be 13/80 .
If so, then the common denominator is 40d, and 'd' turns out to be 13/80 .