Jerry is painting a fence made of 4 wooden planks. He has 4 different colours to choose from. He randomly chooses a colour for each plank. What is the probability that all 4 planks are not the same colour?

Nina has prepared the following two-column proof below. she is given that ∠oln ≅ ∠lno and she is trying to prove that ol ≅ on. triangle oln, where angle oln is congruent to angle lno nina made two errors in the proof. identify and correct the errors.