Final answer:
Bernie would need to sell at least 18 cups of lemonade to make a profit of at least $20.
Step-by-step explanation:
To find the number of cups Bernie needs to sell to make a profit of at least $20, we need to set up an inequality. Let x represent the number of cups Bernie sells. The profit Bernie makes is given by the equation 1.50x - 6.50. So the inequality that represents the situation is 20 ≤ 1.50x - 6.50.
To solve this inequality, we add 6.50 to both sides to isolate the variable. This gives us 26.50 ≤ 1.50x.
Then, we divide both sides of the inequality by 1.50 to solve for x. We get x ≥ 17.67. Since Bernie can only sell whole cups of lemonade, he would need to sell at least 18 cups to make a profit of at least $20.