When you are discussing arithmetic, you can say "Does 2+3 equal 5?" or "What is 2+3?" In a context where you are discussing some specific object, say cookies, you can also say "How many is 2+3?" or. "How many would 2+3 be?" In a context where you are discussing some continuous ("not countable") quantity like money, you could also say "How much would $2 + $3 be?"

What is two plus three? What does two plus three equal? What does two plus three make?

How much is two plus two?