（ただし１と２を合せて１２のような使い方は出来ません。）
61個の解法が見つかりました。
((1+(7+9))-7)=10
((1+7)+(9-7))=10
((1+7)-(7-9))=10
((1+9)×(7÷7))=10
((1+9)+(7-7))=10
((1+9)-(7-7))=10
((1+9)÷(7÷7))=10
((1-7)+(7+9))=10
((7×(1+9))÷7)=10
((7+(1+9))-7)=10
((7+9)+(1-7))=10
((7+9)-(7-1))=10
((7-7)+(1+9))=10
((7÷7)×(1+9))=10
((7÷7)+(1×9))=10
((7÷7)+(9÷1))=10
((9+(1+7))-7)=10
((9+(7÷7))÷1)=10
((9-7)+(1+7))=10
((9÷1)+(7÷7))=10
(1×(9+(7÷7)))=10
(1+((7×9)÷7))=10
(1+((7+9)-7))=10
(1+(7×(9÷7)))=10
(1+(7+(9-7)))=10
(1+(7-(7-9)))=10
(1+(7÷(7÷9)))=10
(1+(9×(7÷7)))=10
(1+(9+(7-7)))=10
(1+(9-(7-7)))=10
(1+(9÷(7÷7)))=10
(1-((7-7)-9))=10
(1-((7-9)-7))=10
(1-(7-(7+9)))=10
(7×((1+9)÷7))=10
(7+((1+9)-7))=10
(7+(1+(9-7)))=10
(7+(1-(7-9)))=10
(7+(9+(1-7)))=10
(7+(9-(7-1)))=10
(7-((7-1)-9))=10
(7-((7-9)-1))=10
(7-(7-(1+9)))=10
(7÷(7÷(1+9)))=10
(9+((1×7)÷7))=10
(9+((1+7)-7))=10
(9+((7÷1)÷7))=10
(9+((7÷7)÷1))=10
(9+(1×(7÷7)))=10
(9+(1+(7-7)))=10
(9+(1-(7-7)))=10
(9+(1÷(7÷7)))=10
(9+(7×(1÷7)))=10
(9+(7+(1-7)))=10
(9+(7-(7-1)))=10
(9+(7÷(1×7)))=10
(9+(7÷(7÷1)))=10
(9-((7-1)-7))=10
(9-((7-7)-1))=10
(9-(7-(1+7)))=10