Please help me! When explaining, make it easy to understand!

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 .

Select the correct answer from the drop-down menu. this graph represents the inequality x+2< 4,2x> 3,x+6< 12,2x> 12

Which shows the graph of the solution set of 3y – 2x > –18?