The answer is C), 834, 834.19, 834.2, 834.29
I know this is late, but I hope it was helpful!
John brought 20 water melons each water melon cost him 2 dollars. He gave his friend Bob 3/4 of the watermelons. In return bob gave him double the amount of water melons back. How many watermelons does John have now? How much money did he spend on each water melon?
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:

Y is directly proportional to x and therefore takes the form y=kx where k is the constant of proportionality.
Dividing both sides by x for the given values, k becomes 18/4 = 4.5