(ただし1と2を合せて12のような使い方は出来ません。)
36個の解法が見つかりました。
((3+5)+(9-7))=10
((3+5)-(7-9))=10
((3+9)+(5-7))=10
((3+9)-(7-5))=10
((3-7)+(5+9))=10
((5+(3+9))-7)=10
((5+9)+(3-7))=10
((5+9)-(7-3))=10
((5-7)+(3+9))=10
((9+(3+5))-7)=10
((9-7)+(3+5))=10
(3+((5+9)-7))=10
(3+(5+(9-7)))=10
(3+(5-(7-9)))=10
(3+(9+(5-7)))=10
(3+(9-(7-5)))=10
(3-((7-5)-9))=10
(3-((7-9)-5))=10
(3-(7-(5+9)))=10
(5+((3+9)-7))=10
(5+(3+(9-7)))=10
(5+(3-(7-9)))=10
(5+(9+(3-7)))=10
(5+(9-(7-3)))=10
(5-((7-3)-9))=10
(5-((7-9)-3))=10
(5-(7-(3+9)))=10
(9+((3+5)-7))=10
(9+(3+(5-7)))=10
(9+(3-(7-5)))=10
(9+(5+(3-7)))=10
(9+(5-(7-3)))=10
(9-((7-3)-5))=10
(9-((7-5)-3))=10
(9-(7-(3+5)))=10