Please help me please !! The answer isn’t a!

(if f(x)=4x^2 and g(x)=x+1, find (f o g)(x)

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 diagram shows lines that must be parallel lines cut by transversal?