Help please.. I don’t understand. thank you <3

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 following graphs represents the function f(x) = 2^x

What is the solution to the system of equations? 10x+3y=8 -9x-y=-20 (11, 1) (1, 11) (–1, 11) (11, –1)'