Answer:
z = 50
Step-by-step explanation:
There are 4 numbers in total (5,10,15,z)
The mean is when you get the total of all the numbers and divide by how many there are
If you do the inverse then that means that 20 x 4 = total of all 4 numbers
80 = 15 + 10 + 5 + z
80 = 30 + z
z = 80 - 30
z = 50
You can check you answer at the end
hope this helps :)
