Can somebody please help with this?

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 .

If i had 1234 apples and 1 banana what is the total amount

For the functions f(x) = -922 – 2x and g(x) = -32? + 6x – 9, find (f - g)(x) and (f - ).