Hey there! I'm happy to help!
We want to write this as an expression.
If you see the word sum, it means you add.
Let's say that our number is n. If we have twice of n, we have 2 times n. You can put them right next to each other to show that they are multiplied, so this is 2n.
So, the sum of -8 and twice a number is -8+2n. You can also flip it around to be 2n-8 and it would be the same thing.
Have a wonderful day!
