#### Answer

$\approx$ 14.43 in.

#### Work Step by Step

The radius of each gear = 4 in
The length of the chain = 2 * center distance + 2 * $\frac{circumference of the gear}{2}$
54 in= 2 * center distance+ 2 * $\frac{2\pi r}{2}$
54 = 2 * center distance+ 2$\pi$* 4
54 - 8$\pi$ = 2* center distance
center distnce = 27 - 4$\pi$
center distance $\approx$ 14.43 in.