Answer:
The numbers are 3, 12 and 5.
Step-by-step explanation:
Let the numbers =x, y and z.
The sum of three numbers is 20 implies x+y+z=20----------------i
The second number is 4 times the first implies y=4x--------------ii
The sum of the first and the third is 8 means x+z=8---------------iii
from (i), z=20-x-y---------iv
Put (iv) in (iii),
x+20-x-y=8
20-y=8
y=20-8=12
y=12
Put y=12 in (ii)
4x=y
x=y/4 = 12/4 = 3
x=3
Put x=3 and y=12 in (iv)
z=20-3-12=5
z=5
Therefore, the numbers are 3, 12 and 5.