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