How would i set this up and solve it?

Because they are parallel lines intersected by a common line, they make the same angle in the same parts. So angle HFC and DBC are the same. Therefore you can set them equal to each other and solve. 

5x = 3x +40 > Subtract 3x from both sides
2x = 40 > divide both sides by 2
x = 20

So, the angle HFC must be 100 degrees. 

It is a percent with money involved too divide and you should have your answer

Hello! i hope this
since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. answer. according to the property of cofunctions (topic 3), sin 30° is equal to cos 60°. sin 30° = ½.