Which shows the best use of the associative and commutative properties to make simplifying 2.4 + 13 – 5 + 3.6 +7 easier?
O A. (2.4 + 13) + (-5 +3.6 + 7)
O B. (2.4 + (-5) + 13) + (7 + 3.6)
O C. (7+ 2.4 + 13) + [3.6+ (-5)]
O D. (2.4+ 3.6) + [13 +7+(-5)]

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 step statement reason 1 ∠oln ≅ ∠lno given 2 draw oe as a perpendicular bisector to ln by construction 3 ∠leo ≅ ∠neo transitive property of equality 4 m∠leo = 90° definition of a perpendicular bisector 5 m∠neo = 90° definition of a perpendicular bisector 6 le ≅ en definition of a perpendicular bisector 7 δole ≅ δone side-angle-side (sas) postulate 8 ol ≅ on cpctc nina made two errors in the proof. identify and correct the errors.