The easiest way is to replace "k" with "5" for each of the options and solve to find out which results in a true statement.
2.4(5 - 1.3) = 15.12 → 2.4(3.7) = 15.12 → 8.88 = 15.12 FALSE
1.1(5) - 1.8 = 7.3 → 5.5 - 1.8 = 7.3 → 3.7 = 7.3 FALSE
1.4(.7(5) + 2) = 2.1 → 1.4(3.5 + 2) = 2.1 → 1.4(5.5) = 2.1 → 7.7 = 7.3 FALSE
1.8(5) + 3.2 = 12.2 → 9.0 + 3.2 = 12.2 → 12.2 = 12.2 TRUE!!!
Answer: 1.8k + 3.2 = 12.2
