Look at the figure below.

What is the value of x?

#you see the straight line near (2x - 4) ? yeah it totals 180°, so you only need to find the degree of the other side.

#The question already show 90° (L) and 48° so you can get the other side degree by minus 180 with the degree known.

180° - 48° - 90° = 42°

#and so you only need find the rest of the degree. The degree of (2x + 4)

180° - 42° = 138°

#So the (2x + 4)° is 138°

2x + 4 = 138

2x = 138 - 4

2x = 134

x = 134 : 2

x = 67

answer: c

because if you look at the chart you can see a pattern and compare it to the question he simplify out your

but i think the formula is f(x)=6x