（ただし１と２を合せて１２のような使い方は出来ません。）
55個の解法が見つかりました。
((2+7)+(8-7))=10
((2+7)-(7-8))=10
((2+8)×(7÷7))=10
((2+8)+(7-7))=10
((2+8)-(7-7))=10
((2+8)÷(7÷7))=10
((2-7)+(7+8))=10
((7×(2+8))÷7)=10
((7+(2+8))-7)=10
((7+7)-(8÷2))=10
((7+8)+(2-7))=10
((7+8)-(7-2))=10
((7-7)+(2+8))=10
((7÷7)×(2+8))=10
((8+(2+7))-7)=10
((8-7)+(2+7))=10
(2+((7×8)÷7))=10
(2+((7+8)-7))=10
(2+(7×(8÷7)))=10
(2+(7+(8-7)))=10
(2+(7-(7-8)))=10
(2+(7÷(7÷8)))=10
(2+(8×(7÷7)))=10
(2+(8+(7-7)))=10
(2+(8-(7-7)))=10
(2+(8÷(7÷7)))=10
(2-((7-7)-8))=10
(2-((7-8)-7))=10
(2-(7-(7+8)))=10
(7×((2+8)÷7))=10
(7+((2+8)-7))=10
(7+(2+(8-7)))=10
(7+(2-(7-8)))=10
(7+(7-(8÷2)))=10
(7+(8+(2-7)))=10
(7+(8-(7-2)))=10
(7-((7-2)-8))=10
(7-((7-8)-2))=10
(7-((8÷2)-7))=10
(7-(7-(2+8)))=10
(7÷(7÷(2+8)))=10
(8+((2×7)÷7))=10
(8+((2+7)-7))=10
(8+(2×(7÷7)))=10
(8+(2+(7-7)))=10
(8+(2-(7-7)))=10
(8+(2÷(7÷7)))=10
(8+(7×(2÷7)))=10
(8+(7+(2-7)))=10
(8+(7-(7-2)))=10
(8+(7÷(7÷2)))=10
(8-((7-2)-7))=10
(8-((7-7)-2))=10
(8-(7-(2+7)))=10