3. [Core content] The next math drawing indicates a make-a-ten method for adding 6 + 8. oooo a. Write equations that correspond to the make-a-ten method for adding 6 + 8 depicted in the math drawing. Your equations should make careful and appropriate use of parentheses. Which property of arithmetic do your equations and the math drawing illustrate? b. Make a math drawing for 7 + 5 that illustrates a make-a-ten method. Write equations that correspond to the strategy indicated in your math drawing, making careful and appropriate use of parentheses. 4. [Core content] Tomaslav has learned the following facts well: " All the sums of whole numbers that add to 10 or less-Tomaslav knows these facts "forward and backward." For example, he knows not only that 5 + 2 is 7, but also that 7 decomposes into 5 + 2 or 2 + 5. - 10 + 1, 10 + 2, 10 + 3, . .., 10 + 10. . the doubles 1 + 1, 2 + 2, 3 + 3, . .., 10 + 10. For each sum in this problem, describe at least three different ways that Tomaslav could use reasoning, together with the facts he knows well, to determine the sum. In each case, write equations that correspond to the strategies you describe. Take care to use parentheses appropriately and as needed. a. 8 + 7 b. 6 + 7 c. 8 + 9 (Try to find four or five different ways to solve this.)