Solve by completing the square, x^2 + 6x - 6 = 0

so mark-up is 0.4 multiplied by 180 = 72

perpendicular to x*4 means it's y = -1/4*x+k

so for y = 7 and x = 2

we have 7 = -1/4*2 + k so k = 7.5

so the equation is   y = -1/4x + 7.5

the coach can choose 4 members to send to competition in 1680 ways. the correct answer between all the choices given is the second choice. i am hoping that this answer has satisfied your query and it will be able to you in your endeavor, and if you would like, feel free to ask another question.