Answer:
4.) 12
Step-by-step explanation:
[tex] \frac{2}{3} (9a + 18b) = 6a + kb \\ \\ \implies \: \frac{2}{3} \times 9a + \frac{2}{3} \times 18b = 6a + kb \\ \\ \implies \: { 6a} + 12b = 6a + kb \\ \\ \implies \: \cancel{ 6a} + 12b - \cancel{ 6a} = kb \\ \\ \implies \: 12b = kb \\ \\ \implies \: k = \frac{12\cancel b}{\cancel b} \\ \\ \huge \implies \: k = 12[/tex]
