is it possible to solve for y using information from the following problems:

 
a + 30= y
b + 28= y
c + 26= y
d + 32 = y
 
 
i'm writing a book (i.e. i'm not great at math) and my protagonist must solve a riddle. the riddle is a magic square, where some (four) of the numbers in the grid are missing. if you are not familiar with what a magic square is, it's a form of recreational math that dates back to the sixth century b.c.e. imagine a 16-square grid filled with numbers where each row, column, and diagonal equals the same number when added together. for example:
 
a   14    15   19    7     b     125    11   10    c 16   d    3    13
 
if our protagonist can figure out what y equals, he can easily figure out the missing numbers through simple algebra. i've simplified the problem above by adding the rows and columns together. also, no two numbers are ever repeated in a magic square. not sure if that helps. 
 
how dead is my protagonist?
 
 

you want y to be equal to 34
a=4, b=6, c=8, and d=2
 
4  14  15  1
9   7   6  12
5  11  10  8
16  2   3  13