If a, b and c are positive integers and (a - b)c = 0, which statement must be true?
a = b
a < c
b > a
b = c
State, Whether the following statements are true of false.
(i) If a<b, then a−c<b−c
(ii) If a>b, then a+c>b+c
(iii) If a<b, then ac>bc
(iv) If a>b, then ac<bc
(v) If a−c>b−d; then a+d>b+c
(vi) If a<b, and c>0, then a−c>b−c where a, b, c and are real numbers and c≠0.