All motorcyclist wear helmets , i need to write this as in a conditional statement

Elijah brought a total of 16 pounds of peanuts and cashew nuts and paid $49.50. if peanuts cost $2.75 per pound and cashew nuts cost $3.25 per pound, how many pounds of cashew nuts did he buy?

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 .

Brent wants to know what is 5 x 1/2