Hi can someone PLEASE help only if you know the process of these problems?? if i get higher scores on this ixl quiz it will really benefit my grade! i would really appreciate it answer has to be in simplest radical form

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.