Your initial instinct would be to solve this problem with this solution. 34 x 57 = 1,938 petals.
However, the word estimate is present; therefore, we have to consider that we need to get the approximate number and not the exact number of petals.
There is a general rule regarding estimation or approximation. You have to round it to the nearest place you have based on. In this problem we round it off to the nearest tens place.
If the number is below 5, you round it down: 34 is rounded down to 30 petals.
If the number is above 5, you round it up: 57 is rounded up to 60 sunflowers.
Thus, your equation would be : 30 x 60 = 1,800 petals (best estimate)