Answer:
16, 32, 36
Explanation:
If you set up an equation using x as the first number you can solve for x then follow the directions.
For example...
1st number is x
2nd number is 2x
Third number is 2x+4
Put it all in an equation to solve for x:
x + (2x) + (2x+4) = 84
Combine like terms, then solve.
5x + 4 = 84
Subtract four from both sides
5x = 80
Divide both sides by 5
x = 16
Now just plug x into the expressions that were created for each number, and you have your answers.
Let me know if you need further explanation.