Answer
651 nm.
Work Step by Step
$$d sin\theta=m\lambda$$
For small angles, the tangent and sine are approximately equal. Consider m = 1. For 2-slit interference, the distance between bright fringes equals the position of the first m=1 bright fringe from the centerline.
The tangent is the spacing from the centerline, x, divided by the distance from the slits to the screen, L.
$$d\frac{x}{L}=(1) \lambda$$
$$x=\frac{\lambda L}{d}$$
Let the red laser be subscript 1, and the laser pointer be subscript 2.
In the 2 cases, the slit spacing d and the distance from the slits to the screen, L, stay the same.
$$x_1=\frac{\lambda_1 L}{d}$$
$$x_2=\frac{\lambda_2 L}{d}$$
$$\lambda_2=\frac{\lambda_1}{x_1}x_2=\frac{632.8nm}{5.00mm}5.14mm\approx 651 nm$$