Hello!
I believe your answer is: 8x + 18y
The solution here is quite simple and easy to understand! All you have to do is combine the terms that are alike each other. For example:
5x + 7x + 8y − 4x + 9y + y
X variable: Bold
Y Variable: Underlined
Therefore, if we combine all terms that have the x variable...
8x + 8y + 9y + y
Now, if we combine all the terms that have the y variable...
8x + 18y
Remember: It's always important to note the symbols you find, such as: "+" or "-"!!
Hope you have a great day and good luck on your studies! :)