-9 + 6 + (-7) +3=
-9 +6 = -3
-3 + (-7)= -10
-10 +3= -7
12 cubic feet!! this may be it
7x+1000+x=89000
7x+x+1000-1000=89000-1000
8x=88000
8x/8=88000/8
x=$11000
1, 3, 5, 7, 9 are the possible digits
meaning you have 5! possible combinations or 120 combinations