MN 62 Translation Request

In "The Longer Advice to Rāhula" the following appears: >Muditaṁ, rāhula, bhāvanaṁ bhāvehi. >Muditañhi te, rāhula, bhāvanaṁ bhāvayato yā arati sā pahīyissati. Bhante Sujato translates this as >Meditate on rejoicing. >For when you meditate on rejoicing any discontent will be given up. Thanissaro Bhikkhu: > “Develop the meditation of empathetic joy. For when you are developing the meditation of empathetic joy, resentment will be abandoned. Bhikkhu Vagga: > "Rāhula, develop meditation on altruistic joy; for when you develop meditation on altruistic joy, any discontent will be abandoned. Can somebody please explain which terms correspond to which here, and how the translation is carried out? Thank you