Answer:
a = 3.6
Step-by-step explanation:
[tex] \frac{2}{3} (6a + 9) = 20.4 \\ \\ \bigg( \frac{2}{3} . \boxed{6a} \bigg) + \bigg(\boxed{ \frac{2}{3}} . {9} \bigg) = \boxed{ 20.4} \\ \\ (2.2a) + (2.3) = 20.4 \\ \\ 4a + 6 = 20.4 \\ \\ 4a = 20.4 - 6 \\ \\ 4a = 14.4 \\ \\ a = \frac{14.4}{4} \\ \\ a = \boxed{3.6}[/tex]
