URGENT: What are the two mistakes in this problem?

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 .

Find the vertex of the function given below y=x^2-6x+1

Arecipe calls for 32 fluid ounces of heavy cream. how many 1 pint containers of heavy cream are needed to make the recipe?