Of the 84 parents who attended a meeting at a school, 35 volunteered to supervise
children during the school picnic and 11 volunteered both to supervise children during
the picnic and to bring refreshments to the picnic. If the number of parents who
volunteered to bring refreshments was 1.5 times the number of parents who neither
volunteered to supervise children during the picnic nor volunteered to bring refreshments,
how many of the parents volunteered to bring refreshments?
答案：B