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.
3yds or 5yds is the closest
It’s either B or D.. now you have 2 hopefully this helps
9 it’s the only one single digit number and each number has a 2 digit number or higher