Respuesta :
Hey there! I'm happy to help!
Sum means you add. Let's call our number n.
n+15
We double the whole thing.
2(n+15)
This is equal to something.
2(n+15)=
Difference means you subtract.
2(n+15)=n-6.
Have a wonderful day! :D
2n+15 = n -6 because sum means addition and difference means subtraction