The phrasal verb Add Up can be used to talk about a calculated a total sum: 'The waiter added up the bill and the total sum was $10'.
Add Up is also means to make sense: His theory doesn't add up. 'I don't think he did enough research'.
Add Up To is used to talk about an equaled amount. E.g. 'The total bill added up to $10'.
Affect is a verb, although very rarely it can be used as a noun. Effect can be a verb or a noun, so it's to get them confused.
Try using them like this:
A thing that has happened.
'Watching his favourite team lose had little effect on Julian'.
To bring about change.
'We will effect changes to business policies from next year'.
You're really means ‘you are’, the apostrophe (apostrophe = ') shows us that the ‘a’ is missing:
"You're really boring. I wish I didn’t have to sit next to you all day.”
Your is a possessive pronoun and should be followed by a noun:
‘Your car, your phone…’
One common mistake is to say, ‘Hope your okay’.
It should, of course, be, ‘Hope you're okay’.
