Okay, after I explain the process of finding the answer to this, it will be easier for you! First, you shold understand the key words to math. In this question, fewer is the key word. And fewer means less, so subtraction. Every new row has 2 FEWER tiles than the row below it. So we now to to subtract 2 from EVERY NEW row. So, if the first row has 23 tiles how many tiles will be in the next row. Well, all we have to do is 23 - 2 = 21! There is your answer, I hope I am correct!
(It is your choice to go with my answer being correct or not. I absolutely WILL NOT, and CAN NOT take responsibility for your question being incorrect. Again, it is YOUR choice to choose whether or not you go with my answer. Thank you!) :)
