In the $\Delta KLP$, find $a+b$:
My question is that: isn't some information missing from the question? Because all I can see is is that $ \usepackage{ gensymb }
\angle SKP = \angle LTS = p\degree $.
Am I missing some well known formula ??
Please help me with some hints/guides.

Since the triangles $STL$ and $PKL$ are similar, we know the ratios of their sides are the same:
$$\frac{a}{9}=\frac{10}{b+8}=\frac{8}{12}$$
Hence $a=(9)\frac{2}{3}=6$ and $2b+16=30$, hence $b=7$. Finally we have $a+b=13$.