Answer:
90 couples or 180 ppl
Explanation:
lets take "x" as the couples who remained at the party
we start out with 250:
250
but by the time it is 11pm, 70 people have left the party
since it is a couples party we need to divide by two to account for the couples
=x
250-70=180
180/2=90
so 90 couples or 180 ppl
hope this helps