Let x represents the number of hours spent volunteering in school and y represents the number of hours spent volunteering outside of school.
1. Since each member must spend at least 20 hours doing volunteer work each semester, then
x+y≥20.
2. Since the number (x) of hours spent volunteering at school activities can be no more than twice the number (y) of hours spent volunteering outside of school, then
x≤2y.
You get a sytem of two inequalities:
[tex]\left\{\begin{array}{l}x+y\ge 20\\x\le 2y.\end{array}\right.[/tex]
Consider all pairs:
1. (12.5): 12 is not ≤ 2·5=10 -false;
2. (0,22): 0+22≥20 and 0≤2·22=44 - true;
3. (10,10): 10+10≥20 and 10≤2·10=20 - true;
4. (15,6): 15 is not ≤ 2·6=12 -false;
5. (7,11): 7+11=18 is not ≥ 20 -false;
6. (8,16): 8+16=24≥20 and 8≤2·16=32 - true.
Answer: correct choices are 2, 3 and 6.
