First-grader problem in arithmetic

Question

I found this problem in a text book on arithmetic for first graders (7 y.o.) of the former USSR^* . The problem comes from the section that covers single-digit addition and subtraction. Here is the screenshot of the problem:

This is the entire problem: there is no textual description accompanying it, and of course no answer at the back of the book. Other problems in the section are of the 1 + 6 = and 8 - 7 = kind, so this should be an elementary problem as well. However, I cannot figure out what is being asked here: I do not remember this notation, because we used different text books.

Can anybody figure out what is being asked by this assignment?

---

^* A.S.Pchyolko, G.B.Polyak "Arithmetic" Fifth edition. Text book for the first grade of elementary school. Moscow, Printing house of the Department of Education, 1959

Answer 1

Possibly the student is to produce three numbers by adding the number in the centre of the circle to each of the three around it. (Of course by adding $-6$ I mean subtracting $6$, since I assume that the students had not yet been introduced to negative numbers.) I note that the indicated subtractions are all possible in the non-negative integers, a fact that can be viewed as some small evidence in favor of the interpretation.

Answer 2

I notice the first 2 numbers +6 and -6 can be produced by rearranging the given numbers with + and - signs:

2+4 = 6

10 - 9 - 7 = -6

But the last 2 aren't too clear

Answer 3

Perhaps the problem is to produce the number in the middle of the circle using the numbers on the outside. So $(3 \cdot 4)/2=6, 10-7-9=-6, (3 \cdot 2)+1=7, (8-9) \cdot 7=-7$.