Question

What are the values of a & b?

Answer 1

notice, what you really have is 3 SIMILAR TRIANGLES, the blue line or "altitude" makes 2 smaller triangles, which are similar to each other as well as the big one, containing both of them

so use the corresponding sides to get their ratio, and thus the values for "a" and "b"
one can say that \(\bf \cfrac{b}{6}=\cfrac{10}{8}\)