



 
Hi Amy, In my mind the key here is a good, labeled, diagram. Here is mine. Susan starts at $P$, moves t $A$ which is 20 m away, and the to $B$ from which the rock formation $R$ is directly to her right. This means that the angle $RBA$ is a right angle. Hence triangles $RBA$ and $RBP$ are right triangles. Can you complete the problem now? Write back if you need more assistance.  


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