Answer :
x+y+z=22
(x+y+z+t)/4=8
subsitute
x+y+z=22
(22+t)/4=8
multiplly by 4
22+t=32
subtract 22
t=10
the fourth number is 10
(x+y+z+t)/4=8
subsitute
x+y+z=22
(22+t)/4=8
multiplly by 4
22+t=32
subtract 22
t=10
the fourth number is 10