一道算24点的数学题

1: (5 × 13 + 7) ÷ 3
2: ((5 × 13) + 7) ÷ 3
3: (7 + 5 × 13) ÷ 3
4: (7 + (5 × 13)) ÷ 3
5: (7 + 13 × 5) ÷ 3
6: (7 + (13 × 5)) ÷ 3
7: (13 × 5 + 7) ÷ 3
8: ((13 × 5) + 7) ÷ 3

(-5*(-13)+7)/3=24
(7-5*(-13))/3=24
(7-13*(-5))/3=24
(-13*(-5)+7)/3=24

http://www.dffy.com/tool/24.htm