What is the value of y 72 y

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 a baby uses 15 diapers in 2 days, how many diapers will the baby use in a year?

When using the linear combination metho e linear combination method to solve a system of linear equations, the four options are: