Answer: 875 people
Explanation:
The 375 people seated represent 30% of the total number of people who wanted seats but these ones got them.
This means that the number of people who wanted seats is 70% of the number of people who wanted seats.
Assume the number of people who wanted seats is x:
30% * x = 375
x = 375 / 30%
x = 1,250 people wanted seats.
Those who wanted seats but couldn't get:
= 1,250 * 70%
= 875 people