https://www.bls.gov/ooh/Life-Physical-and-Social-Science/Physicists-and-astronomers.htm
I'd recommend skipping the MPhys and going to physics PhD for the most $$$.
Let me help, it is a pretty basic geometry problem if you know the rules behind it
Assume that the triangles are congruent (scalable to eachother) and that the ratios between the sides remain constant
$$\ AB:AE=AC:AD$$
$$\frac{8cm}{12cm}=\frac{x+8cm}{15cm}$$...