(ただし1と2を合せて12のような使い方は出来ません。)
21個の解法が見つかりました。
((4+4)+(7-5))=10
((4+4)-(5-7))=10
((4+7)+(4-5))=10
((4+7)-(5-4))=10
((4-5)+(4+7))=10
((7+(4+4))-5)=10
((7-5)+(4+4))=10
(4+((4+7)-5))=10
(4+(4+(7-5)))=10
(4+(4-(5-7)))=10
(4+(7+(4-5)))=10
(4+(7-(5-4)))=10
(4-((5-4)-7))=10
(4-((5-7)-4))=10
(4-(5-(4+7)))=10
(7+((4+4)-5))=10
(7+(4+(4-5)))=10
(7+(4-(5-4)))=10
(7-((5-4)-4))=10
(7-(5-(4+4)))=10