Suppose the density of a fluid is 780 kg/m* and flows with velocity i = yî +xj (components of i are measured in m/s). find the rate of flow outward through the

Suppose the density of a fluid is 780 kg/m* and flows with velocity i = yî +xj (components of i are measured in m/s). Find the rate of flow outward through the upper half of the sphere x2 +y2 +z2 = 4. can please someone tell me how to do it ?