In questions 37 to 40, find out the true values of these false statements, that is, the conditions under which these statements are established.

37.a=b

38.a=b and none of them are equal to 0.

39.a= 1 or c=0.

40.ad+bc=0

In questions 4 1 to 44, attribute equality or attribute equality is shown to prove this statement.

The left and right sides of the 4 1. equation are equal, and the exchange does not change this property.

42. Equivalent substitution

43. Equivalent substitution

44. Equivalent substitution

Pure personal understanding