Question 305676
A class consisted of 14 boys and 19 girls.
 On a certain day all the boys was present and some girls were absent, so that
 the girls present made up only 30% of the class attendance.
 How many girls were absent?
:
Let a = no. of girls absent
:
Total in the class: 14 + 19 = 33 students
then
(33-a) = total in the class on that certain day
:
{{{(19-a)/(33-a)}}} = .30
19 - a = .30(33-a)
19 - a = 9.9 - .3a
19 - 9.9 = a - .3a
9.1 = .7a
a = {{{9.1/.7}}}
a = 13 girls absent
:
:
See if that makes sense
Total in class that day: 33-13 = 20
Girls in the class that day: 19-13 = 6
{{{6/20}}} = .3 (30%)