Question

How do I solve C=πd for d

Answer 1

$C=\pi d\\ d=\dfrac{C}{\pi}$

Answer 2

$C=\pi d\\ \\ C\cdot \frac { 1 }{ \pi } =\pi \cdot \frac { 1 }{ \pi } \cdot d\\ \\ \therefore \quad d=\frac { C }{ \pi }$