Answer:

Explanation:
For this exercise you need to use an Inverse Trigonometric Function called "Arctangent".
By definition:

You must observe carefully the triangle PQR shown in the picture attached.
In this case you can identify that:

Therefore, knowing those values you can substitute them into
, as following:

Finally, evaluating, you get that the measure of the angle R is the following:

Rounding to the nearest tenth:
