Answer: D. 400 + 500 + 600 + 700
Explanation:
The expression that best give the total estimate of the number in attendance of the high school musical would be gotten by rounding up or down to the nearest hundred.
If the figure in the tens position is greater than 50, we round up to the nearest hundred;
If the figure in the tens position is less than 50,we round down to the nearest hundred.
As such, 375 will be rounded up to 400
480 will be rounded up to 500
621 will be rounded down to 600 and lastly,
685 will be rounded up to 700.
The expression therefore is 400 + 500 + 600 + 700 making option D the right option.