The average of X1, x2, x3, x4 is 16. Half the sum of X2, x3, x4 is 23. What is the value x1?

None

Given:

(x1 + x2 + x3 + x4) / 4 = 16

Multiply both sides by 4:

x1 + x2 + x3 + x4 = 64 ... (Equation 1)

Also, (x2 + x3 + x4) / 2 = 23

Multiply both sides by 2:

x2 + x3 + x4 = 46 ... (Equation 2)

Now, substitute Equation 2 into Equation 1: x1 + 46 = 64

Subtract 46 from both sides: x1 = 18

Therefore, the correct answer is: 18