Answer:
89 seats are not being used
Explanation:
You subtract the seats being used by teachers
342 - 75 =267
Change 2/3 into a percentage = 66.6%
Find 66.6% of 267= 177.8 (I rounded up to 178)
Then subtract 177.8/178 from 267 to find the amount of seats not being used.
The amount of seats not being used would come down to 89 seats.
I hope this helps!