Write the equation of a line that is perpendicular to y = -1 and that passes through the point (8,-4)

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

Iam trying to solve a linear equation for the shoe size of someone 84" tall taking into consideration example 1 is 69" tall with a shoe size of 9 and example 2 is 72 inches tall with a shoe size of 11. i understand that the equation should be y=mx+b and that on the graph the answer is (3,2) but i just don't understand how to create the equation to solve for 84-inches and 60-inches tall questions. after two days, i need .

Which of the functions graphed below has a removable discontinuity?