1) oui, je leur dis la vérité je dis la vérité à qui = à mes parents = 3éme p. plural = leur = them I told them the truth
2) oui, nous lui parlons nous parlons à qui ? à notre employeur = lui 3ére p. sing = lui
vous parlez à votre employeur = votre = your are you talking to your employer ? Yes, we're talking to him
3) oui elle vous écrit une lettre.(nous = 2ère p. pluriel) is she writing us a letter ? Yes, she is is writing you a letter you = vous (2eme p. sing masc.
lui would have been him = you're writinfng him a letter me would have been : vous m'écrivez une lettre = you're writing me a letter hope I helped !!