Answer:
any non-zero value
Step-by-step explanation:
The equation simplifies to ...
[tex]\dfrac{749}{d}\cdot\dfrac{d}{749}=1=\dfrac{749}{749}\cdot\dfrac{d}{d}\\\\1=1 \qquad\text{$d\ne 0$}[/tex]
Any non-zero value of d will make the equation true.
