When a question tells you to find the total of something it is usually means you need to add to add decimals you align the decimals and if a number doesn't have a decimal you add .0 on the end then line it up. It also might help to add a 0 in empty spots . Then you move the decimal to the same place in the solution and add like normal.
4y and 3y are like terms because they have y after the number. Every time when a math problem ask you to combine like terms, it'll be the ones that have the same variables or powers.
