This question is wrong. The correct rule should be that the sum of the two numbers below each triangle+1 equals the number above. In other words, the number in the lower right corner of the first triangle is 4 instead of 1.

7-2=5,2- 1= 1,7- 1=6,5+ 1+6= 12。

10-3 = 7,6-3 = 3,10-6 = 4,7+3+4 =14, and their adjacent △ 12△ 14, with a difference of 2.

Law of addition:

Addition has several important properties. It is interchangeable, which means that the order is not important, it is interrelated, which means that when more than two numbers are added, the order in which the addition is performed is not important. Repeatedly adding 1 is the same as counting; Adding 0 will not change the result. Addition also follows related operations such as subtraction and multiplication.

Addition is one of the simplest digital tasks. The most basic addition: 1+ 1 five-month-old babies and even other animal species can be counted. In primary education, students are taught to calculate the superposition of decimal numbers, starting with one digit, and gradually solving the more difficult number calculation.