Good at isometric views? (you do not have to answer all just one or a few .) ^^

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 basic geometric term has no width, no length, and no thickness? line b. point c. angle d. plane

Find the constant of variation for the relation and use it to write an equation for the statement. then solve the equation.