Answer:
Question 1) 6x+5
Question 2) Blank #1: sum. Blank #2: 5. Blank #3: 4
See work in the attachment. If you're still confused, read the step-by-step explanation for a more in-depth explanation of what exactly I did for my work. Let me know if you have any questions :>
Explanation:
For question 1, it's important to know that the perimeter is equal to the sum of all the sides. Since the shape is a rectangle, the sides opposite of each other are the same length. Thus, the left and right sides are both 3x - 3. 2(3x - 3) = 6x - 6. The unknown value, which I called a, is the same for both the top and the bottom. To find it, you must first subtract 6x - 6 from the perimeter of 18x + 4. This equals 12x + 10. Then, divide that answer by 2 to get the unknown side. You then get 6x + 5 as the answer for the unknown side.
To make sure it's correct, you can plug in a random number for x. In this case, I checked my work by plugging 2 in for x.
Perimeter = 18(2) + 4 = 36 + 4 = 40
Perimeter = 6(2) + 5 + 6(2) + 5 + 3(2) - 3 + 3(2) - 3 = 12 + 5 + 12 + 5 + 6 - 3 + 6 - 3 = 24 + 10 + 12 - 6 = 40
For question 2, the main idea you need to know is that A = lw. The area of the first rectangle is 6 * 5 = 30. The area of the second rectangle is 6 * 4 = 24. When you add them together, you get 54. The area of the rectangle that is formed when you combine rectangle 1 and rectangle 2 is 6 * 9 = 54. This shows that 6(4) + 6(5) = 6(9)