What value correctly fills in the blank in the equation 16 + 12 = 4 ´ ( __ + 3) to show the sum of the two areas of flowers?

Well, the last part if your sentence, "to show the sum of the two areas of flowers?", is irrelevant to the equation. Let's focus on just the equation: 16 + 12 = 4(_ + 3). Though I have no idea what the apostrophe means, I'll assume you meant to put an '*' or asterisk, meaning multiply. Firstly, whenever you have a variable, or a number you want to solve for, replace the blank with a letter like x. It would look like this: 16 + 12 = 4(x + 3). Using PEMDAS or Parentheses, Exponents, Multiply, Divide, Addition, Subtraction, let's address our parentheses. To solve the parentheses, simply multiple 4 with both x and 3 like so: 4(x + 3) = 4x + 12. Our equation will come out something like this: 16 + 12 = 4x + 12. Next, we can subtract 12 from both sides to simplify our equation: 16 = 4x. From there, divide both sides by 4 and you will get: 4 = x or x = 4. That's your answer! If you have any questions, feel free to ask.