An inequality can be formed by simply translating the problem statement to numerical expressions.
From the problem we know that

added with

hours should be equal or greater than

(helpful insight from the keyword "at least"). Therefore, it's inequality would look like:

(>= is used instead of ≥ for constraints in formatting)
The inequality above best models the situation.
1400, as 1200 + 200 = 1,400 and 1600 - 200 = 1400.
The volume of the original cylinder is
... V = π·r²·h
For r=1 and h=1, this is
... V = π·1²·1 = π
For the new cylinder, the volume is 1.089 times that amount.
... V = 1.089π = π·1.1²·(1-k)
... 1.089/1.21 = 1-k
... k = 1 - 1.089/1.21 = 1 - 0.9 = 0.1 = 10%
The appropriate choice is (B) 10.
18/24 = pink roses... 75% of the roses are pink.