It rained on exactly 7 of the days during Jane's summer holiday trip. On
each day that it rained, it rained either in the morning or the afternoon
but not both. There were exactly 5 afternoons when it did not rain and
exactly 6 mornings when it did not rain. How many days did the trip
last?  Choices
A) 7
B) 8
C) 9
D) 10
E) 11
Let M be the number of days it rained in the morning; A - the number of   days it rained in the afternoon; and let N be the number of days when it did not rain.   We have M + A = 7 (days when it rained); M + N = 5 (afternoons when it did not   rain); and A + N = 6 (mornings when it did not rain). Adding the equations we get   2(M + A + N) = 18, M + A + N = 9.   correct answer 9
<result>C</result>
It rained on exactly 7 of the days during Jane's summer holiday trip. On
each day that it rained, it rained either in the morning or the afternoon
but not both. There were exactly 5 afternoons when it did not rain and
exactly 6 mornings when it did not rain. How many days did the trip
last?