Could someone please show me the correct way to answer this

Could someone please show me the correct way to answer this problem? I have been looking through my book for this class and have found no problems like this one. I\'m just not sure where to start given a picture. I have only worked out problems like this with equations. I would really appreciate some help on this.

The mean camber line of a particular thin airfoil may be approximated by three straight-line segments as shown in the sketch. The camber ratio is 5%. Find au Answer: a -0.11 rad mean can line

Solution

The answer for the following given problem is as follows .

The final answer I got is (-.124)rad.

While solving the problem I get this value.