Hey there mate!
Please check the attached answer of picture for explanation.

Wait, do you mean that y=10 is what you want in slope intercept form? Oh btw I'm not answering this just for the points. I'll actually answer the question
The most familiar case is that where you see a " + " sign between two numbers; that's an indication to add the two numbers (or terms) together.
Also, the instruction, "sum up the following," is a command to find the sum of all the numbers that follow.
Rectangular prism rectangular prism