You already have the answer. It is "One type of proof is a two-column proof. It contains statements and reasons in columns. Another type is a paragraph proof, in which statements and reasons are written in words. A third type is a flowchart proof, which uses a diagram to show the steps of a proof." which looks correct to me.
If you are using half as much milk every day, you'll never run out because you'll just keep using half as much. You still won't run out with the coffee shop problem or the refrigerator problem.
Since the ratio of Boys to Girls is 4/3, set this equal to X number of boys/36. Cross multiply so 36*4=144, and 3*x= 3x. So now you have 144=3x, divide by 3 to get x=48 boys.
