I need to solve for each variable lol help

The sum of two numbers is 12 and their difference is 18 what are the two numbers

Draw a tape diagram to represent each situation.for some of the situations,you need to decide what to represent with a variable andre bakes 9 pans of brownies.he donates 7 pans to the school bake sale and keeps the rest to divide equally among his class of 30 students

Paul’s car is 18 feet long. he is making a model of his car that is 1/6 the actual size. what is the length of the model?