One day Mahi went to the river bank with a spear to catch fish. He sat on the bank of the river. At that time a wonderful thing happened. He saw a fish at an angle of $30^{\circ}$ with the plane of the water. However, he has to catch the fish today. Now, the question is, at what angle with the plane does Mahi have to throw the spear to catch the fish, where the relative refractive index of water is $4/3$.