To find the mean you add all the numbers and divide by how many numbers there are so in this case 2+3+4+4+6= 19, there are 5 numbers so divide 19/5
5 is the correct answer.
To prove it, subtract 5 from 18 - You'll get 13.
5 x 2 + 3 = 13.
Use the Angle measurements to find x measure
x + 12/x + 2 = x/x + 8 <- multiply each side by x
x^2 + 12 + 2x = x + 8 <- rearrange
x^2 + x +4 = 0
Your formula is incorrect as,