Answer:
The right system is a + b ≥ 30 , b ≥ a + 10
Step-by-step explanation:
∵ The sum of them is at least 30 means the smallest value is 30
∴ Their sum is a + b = 30 or greater than 30
∴ a + b ≥ 30
∵ Their difference is at least 10 and the greater is b
∴ b - a = 10 or greater than 10
∴ b - a ≥ 10
∴ b ≥ a + 10
So the right system is the first answer
a + b ≥ 30 , b ≥ a + 10
