Answer: 
<u>Step-by-step explanation:</u>
"At least one girl" means P(1 girl) + P(2 girls) + P(3 girls) or 1 - P(all boys)
I will use the latter: 1 - P(all boys)
P(all boys) = 

24 Blue marbles.
Explanation:
56 - 8 = 48
48 / 2 = 24
so if there are 24 blue marbles, 24 x 2 = 48, and then 8 more is 56.
Let x represent the number of students in Janelle’s group.
If Janelle brings 3 markers for each person in her group, then she brings 3x markers for x students. You also know that she brings <span>5 extra markers for everyone to share. Thus, the total amount of markers she brings is 3x+5.
</span>
If Janelle brings in 23 markers in all, then the equation <span><span>3x+5=23 </span> represaents the mathematical model. </span>
3x=23-5,3x=18,x=6
Answer: there are 6 students in Janelle's group.