In the image, there are six triangles, and each of them follows a specific rule involving the numbers placed inside and outside the triangles. You are asked to find the values of $A$, $B$, and $C$ for the three incomplete triangles.

Looking at the patterns:

• Each triangle has three external numbers on the outer sides and three internal numbers inside the triangle.
• By analyzing the relationship between the internal and external numbers, we can determine a consistent rule.

Pattern:

Let's observe the first triangle in the upper left:

• External numbers: $-4, -4, -15$
• Internal numbers: $-7$

Checking the relationships in the next few triangles will help to deduce the rule.

Let me analyze the numbers carefully and find the values of $A$, $B$, and $C$.It appears that for each triangle, there is a relationship between the sum of the external numbers and the internal number. Specifically, the difference between the sum of the external numbers and the internal number varies, but we can look for a pattern:

• **Triangle