Question

the average of four number is 16 and the first three are 12 15 17.

Answer 1

Answer:

(12+15+17+x)/4=16

34+×=16×4

×=64-34

=30

Answer 2

Answer:

[12+15+17+x]/4=16

44+x/4=16

44+x=16×4

44+x=64

x=64-44

x=20

so the fourth number is 20

.......hope u understand........