import math


def vel_sat(k_sat: float, rho_sat: float, mu: float) -> tuple:
    """
    Estimate the seismic velocities after Gassmann fluid substitution using density and
    elastic moduli of saturated rock.

    :returns:
        vp_new : P-wave velocity,
        vs_new : S-wave velocity
    """
    f = 3280.84
    vp_new = math.sqrt((k_sat + (mu * 4 / 3)) / rho_sat) * f
    vs_new = math.sqrt(mu / rho_sat) * f

    return round(vp_new, 2), round(vs_new, 2)