Answer: 10 and 30
Step-by-step explanation:
Assuming the first number to be 'x'. The second number being '3x'.
Arithmetic Mean of 2 no. is (a+b)/2...Here it will be (x+3x)/2 = 20.
Solving for 'x' we get 10 from simplifying it to 4x/2=20.
Therefore the two numbers are : x=10 and 3x=30