Question 50966
8+(36+ ___ )+1=15

8+(36+ n)+1=15
8+36+ n+1=15 [Combine like-terms]
44+n+1=15
45+n=15
45-45+n=15-45 [Solve for n]
n=-30
.
Plugging (n=-30) back into the original equation:
8+(36+ (-30))+1=15
15=15

I also don't understand how the only choices are (0,5,6,7).  Please let me know if this works!!