Construct argument comparing the numbers 492111 and 409867

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. i can't figure out this question. give an explanation too. .

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.