Pwease help .

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 .

Me with this one question, and i'll upvote the brainliest answer

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.