Triangle Ratio/Proportions Problem I would like someone to verify that I am solving this problem correctly. I do not remember the theorem that allows me to make the two halves of the triangle proportional. 
Because (h1/h2 = h1/h2) Triangles are proportional? 
Here is the problem:

My work:


$$\frac{Area(BML)}{Area(BCM)}=\frac{LM}{MC} \Rightarrow \frac{5}{10}=\frac{LM}{MC}$$
$$\frac{Area(MCK)}{Area(BCM)}=\frac{KM}{MB} \Rightarrow \frac{8}{10}=\frac{KM}{MB}$$

Let's say the area of $AMK$ be $2A$ then from $\frac{Area(ALM)}{Area(AMC)}=\frac{LM}{MC}$, the area of $ALM$ will be $4+A$. Now
$$\frac{Area(AMK)}{Area(ABM)}=\frac{KM}{MB} \Rightarrow \frac{2A}{5+4+A}=\frac{4a}{5a}\\\Rightarrow 10A=36+4A\Rightarrow A=6 \Rightarrow S=4+A+2A=22$$
