Aclassroom contains an equal number of boys and girls. if 9 girls leave, twice as many boys as girls remain. what was the original number of students present

So,

since the amount of boys that remain is twice the amount of girls that left:
Its, 9X2=18
18 boys
(we can assume that the amount of girls that left is equal to the amount that remains)

And since the amount of girls is = to the amount of boys,
its 18+18=36

So the original amount of students present is 36 students

Hope this helps!

A) The first three terms are 22, 24, 26
B) There are 15 terms in this sequence that are less than 50