It’s the answer is gotta be it has to be c
The three scores are 86, 74, and an unknown score x. The average (i.e. the sum divided by how many there are) is 80, so we have

Multiply both sides by 3 and you get

Subtract 160 from both sides to get

Note: you could solve this exercise very quickly if you notice that the two numbers, 86 and 74, are symmetrical with respect to 80, which is the average. So, the third number must be the average.
You would have to share a picture or the details of this triangle in order for me to help
Answer:
x= -6
Step-by-step explanation:
5x-8x=14+4
-3=18
x= -6