Question 126563
Let x = second number 
Let x + 12 = first number 
Let 2x - 20 = third number (twenty less than two times the second

Set up the equation - the sum of the numbers is:
1st number + 2nd number + 3rd number = -48
{{{(x + 12) + (x) + (2x - 20) = -48}}}
Combine like terms and solve:
{{{4x - 8 = -48}}}
{{{4x = -40}}}
{{{x = -10}}}
-10 is the SECOND number 
Substite:
{{{x + 12 = -10 + 12 = 2}}}First number 
{{{2x - 20 = 2(-10) -20 = -40}}} Third number 

Check:
{{{(x + 12) + (x) + (2x - 20)= -48}}}
{{{(-10) + (2) + (-40) = -48)}}}
{{{-48 = -48}}}
This checks out.  The three numbers are -10, 2 and -40