Question 16251
first solve the brackets (BODMAS)
so will have 5-y+6-y-5+y=0
           =>5+6-5-y+y-y=0
           =>11-5-2y+y=0
           =>6-y=0
           => -y=-6 (cross out the negative signs)
           => y=6

Check
 
     (5-y)+(6-y)-(5-y)=6
     (5-6)+(6-6)-(5-6)=6
      5-6+6-6-5+6=6
       5-6-5=6
        6=6