How much of each ingredient would u need to make an identical recipe for 8 people? 32 people

What number must you add to complete the square x^2+12x=16

Asalad dressing recipe calls for 1 teaspoon of vinegar and three tablespoons of olive oil to only make 1/3 of the recipe for a single portion how much of each ingredient would you need

Write a linear funtion f with the values f(2)=-1, and f(5)=4