Answer:
[tex]a=\frac{K}{4+9b}[/tex]
Step-by-step explanation:
[tex]K=4a+9ab[/tex]
Switch sides:
[tex]4a+9ab=K[/tex]
Factor out a:
[tex]a\left(4+9b\right)=K[/tex]
Divide both sides by: [tex](4+9b)[/tex]
[tex]\frac{a\left(4+9b\right)}{4+9b}=\frac{K}{4+9b}[/tex]
[tex]a=\frac{K}{4+9b}[/tex]
