1 pound of broccoli will cost 15 cents more than 1 pound of carrots.
To get the price of 1 pound of (something), you divide the existing amount of it by itself to get 1. For example, you have 2.4 pounds of carrots, so divide 2.4 by 2.4 to get 1 pound of carrots.
Next, you divide the price by the weight, so in this case it's $1.68 divided by 2.4 to get the price of 1 pound of carrots, which is 0.70 or 70 cents.
Apply to broccoli, find the price of 1 pound of broccoli, figure out the difference and there's your answer of 15 cents more :)