a) 2 + 3 - 6 = 10 + 4 ⇒ -1 = 14
This is a false statement so it has NO SOLUTIONS, which means it is a CONTRADICTION
b) 17 + 5 = 23 + 4 - 6 ⇒ 25 = 21
This is a false statement so it has NO SOLUTIONS, which means it is a CONTRADICTION
c) 7 + 4 = 5 + 8 + 2 - 10 ⇒ 11 = 5
This is a false statement so it so it has NO SOLUTIONS, which means it is a CONTRADICTION
NOTE: When they make a true statement, then it has infinite solutions and is an Identity