Reason: In the figure 1, the box represents 1, the circle represents 2, and the box is outside, which is the addition of 1+2=3.

In Figure 2, the figure is the same as Figure 1, except that the box is inside, which is the subtraction of 2- 1= 1.

In Figure 3, the boxes are outside, and they are added. Therefore, the triangle represents 5, 1+5 = 6.

Figure 4, inside the box, outside the triangle, subtraction, 5- 1=4.

Figure 5, triangle outside, circle inside, this is subtraction, 5-2=3.

Deduction: The rule is that two figures will be subtracted if they intersect, and added if they don't.

Since there are no negative numbers in primary schools, the square or circle of the first number is 1, 2 or the sum of 0 and 3.

As determined in the second figure, add 1, 2, so the triangle represents 5 or 4.

According to the fourth figure, the triangle is 5, the square is 1 and the circle is 2.

5+2=7

In other words, unconnected inside and outside is "positive" and connected is "negative".

Square+circle =3, circle-square = 1.

Circle =2, square = 1

The second group, triangle+square =6 triangle =5.

Triangle-square =5- 1=4

Verification reasoning

So, the question is: triangle+circle =5+2=7.

But the right one is the first one.