"Three plus two equals five."
Translation:cha' boq wej; chen vagh.
Note that addition is commutative (the numbers can "commute" back and forth) and the order is not important. Also note that subtraction is not commutative (the numbers can not "commute" back and forth), the order is important.
For adding, you can actually put the number in either order. The "Best Translation" has the "three" in a subject-like position in both languages (i.e. first in English and after the verb in Klingon), but both orders are accepted as correct answers on this sentence. Note that the first number, in the English sentence, is not actually the full subject and this is an artificial correlation. An argument could be made for switching out the "Best Translation", but this is the way we have decided to write this sentence. Since we accept both versions, it's not that big a deal.
For subtraction, English puts the starting number first and then the number being subtracted after the "minus". This order cannot be reversed and if you do try to reverse them you wind up with a different result. The Klingon verb is clear that the subject is the thing being disassociated from the object, so the starting number is the object (i.e. appears before the verb) and the number being subtracted is the subject. This order cannot be reversed and if you do try to reverse them you wind up with a different result. Coincidentally this winds up with the orders of the numbers matching in English and in Klingon. Another good example of why you can't just get in the habit of reading Klingon backwards.