Answer: below in picture
explanation: also in picture
Answer:
Step-by-step explanation: 5/10=1/2 - if one student are chosen, who plays soccer
4/9 if then the second student are chosen, who plays soccer
1/2*4/9=2/9 the probability that both students play soccer
X + x+1 + x + 2 = 20
3x + 3 = 20
3x = 17 but can't start with x = 6 because 6+7+8 > 20,
so have start with 5 + 6 + 7 = 18 are the 3 sides.