The average of eight numbers 15,10,13,19,18,21,7 x is equal to 16 what is the value of x

Question

The average of eight numbers 15,10,13,19,18,21,7 x is equal to 16 what is the value of x

Answer 1

(7 + 10 + 13 + 15 + 18 + 19 + 21 + x)/8 = 16

Multiply by 8:

7 + 10 + 13 + 15 + 18 + 19 + 21 + x = 128

Combine terms:

103 + x = 128

Subtract 103:

x = 25