If Jackie works x hours as a tutor, which pays 12 dollars per hour, she earns 12x dollars. If Jackie works y hours as a lifeguard, which pays 9.50 dollars per hour, she earns 9.5y dollars. Thus the total, in dollars, Jackie earns in a week that she works x hours as a tutor and y hours as a lifeguard is 12x+9.5y. Therefore, the condition that Jackie wants to earn at least 220 dollars is represented by the inequality 12x+9.5y≥220. The condition that Jackie can work no morethan 20 hours per week is represented by the inequality x+y≤20. These two inequalities form the system shown in choice C. Choice A is incorrect. This system represents the conditions that Jackie earns no more than 220 dollars and works at least 20 hours. Choice B is incorrect. The first inequality in this system represents the condition that Jackie earns no more than 220 dollars . Choice D is incorrect. The second inequality in this system represents the condition that Jackie works at least 20 hours.