Regrouping numbers into various place values

we have four thousand five hundred equals three thousands plus how many hundreds question mark hundreds so let's write this left hand side but I'm going to write it out in terms of thousands and hundreds so I'll write the thousands in orange so this is equal to this is equal to four thousands which is the same thing as just four thousand plus five hundred which you could also view as five hundreds plus five hundred so this is the left hand side now let's look at the right hand side we have three thousands so it's three three thousands now let's not even look at this right now let's just think about what do we have to add to this right hand side in order to get the same thing that we have on the left hand side well if you compare the three thousand and the four thousand you see you have an extra thousand over here so let's add an extra thousand on the right so we're going to add one extra thousand and now we just have three thousand plus one thousand this is make this makes it the four thousand but then of course we also need another five hundred so we're going to need plus a five hundred right over here so in order for these two things to be equal we to say four thousand four thousand plus 500 plus five hundred is equal to is equal to 3000 3000 plus one thousand five hundred plus one thousand five hundred now the way they've set this up we need to Express so it almost looks the same on the left hand side this is forty five hundred so this right over here this is the same thing as four thousand five hundred this is this right over here and on the right hand side we have three thousands so that's this right over here that's the three thousands and then we just need to express this as hundreds so 1500 this is the same thing as fifteen hundreds so let's rewrite everything we can rewrite this as saying four thousand five hundred just to get the exact same form that they wrote it over there so we could write four thousand five hundred is equal to three thousands three thousands plus now we have to just write this in terms of hundreds well the is 1500s literally if you took 15 times 100 it's going to be equal to 1500 so this could be viewed as 1500s so plus 15 hundreds 100 so in this situation the question mark is equal to 15