What number has to be added to each term of 3: 5 to make the ratio 5: 6?

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 .

How do you summarize data in a two-way frequency table?

0if x and y vary inversely and y=6 as x=7, what is the constant of variation?