Indices-find The value of 6*7^3​

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 .

Negative 5 1/12 + negative 4 1/4 + 6 3/4

18 16 11 45 33 11 33 14 18 11 what is the mode for this data set