Answer:
400.
Explanation:
The given expression is

First, we multiply the product in the numerator, then we divide.

However, this result has more than one significant figures, it has 4 significant figures.
Remember that significant figures refers to those numbers that offer impotant information about a measurement. For example, if we measured a length of 0.00623 kilometers, the digits that gives information about the measurement are 623, so the number has 3 significant numbers.
So. if we want to do an estimation with 1 significant number, we need to round the number to 400, because it's closer to 400 than 300.
Therefore, the estimation of the answer with 1 significant number is 400.