Question 1143
 First of all, convert 3|y+51|-15=6 to
 3|y+51| = 21 by adding 15 on both sides
 then dividing by 7:
 |y + 51| = 7 
 By definition of absolute value,we see that |x| = b  is equivalent 
 to the equations x = b or x = -b.

 Hence,|y + 51| = 7 is equivalent 
 to y + 51 = 7...(1) 
  or y + 51 = -7...(2) 
 From (1): y = -44
 From (1): y = -58