The sum of two positive integers, a and b, is at least 30. the difference of the two integers is at least 10. if b is the greater integer, which system of inequalities could represent the values of a and b? a b ≥ 30 b ≥ a 10 a b ≥ 30 b ≤ a – 10 a b ≤ 30 b ≥ a 10 a b ≤ 30 b ≤ a – 10