TIME REMAINING 57:18
A parabola has a vertex at (0,0). The focus of the parabola is located at (4,0).

What is the equation of the directrix?

x=−4
y=−4
x=4
y=4

The cost varies directly with the number of tickets purchased. it costs $145 for 10 people to attend a concert. a. what is the constant of proportionality (k)? b. write the direct variation equation. c. home much does it cost for 8 people? d. graph this situation. be sure to label each axis and give the graph a title.