Lines ab and cd are parelell enter the measures of the angles in traingle abf

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 .

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3

Which is the graph of f(x) = (4)x? image for option 1 image for option 2 image for option 3 image for option 4