Answer: option c.
Step-by-step explanation:
You need to remember the identity:
The inverse of the tangent function is arctangent. You need to use this to calculate the angle "R":
You know that you need to find the measure of "R" and 
(which is the opposite side) and 
(which is the adjacent side), you can sustitute values into
Then, you get:
33.3 because 27/50=36/x and x=66.67 and thats how much as decayed after 36 hours but you want what is left so subtract from 100 and get 33.3
For each of the following relationships, graph the proportional relationship between the two quantities, write the equation representing the relationship, and describe how the unit rate, or slope is represented on the graph.
X = -5 is the answer I believe
