Answer:
The weight of the lobster is 1 kilogram.
Alexa will pay $25 for her dinner.
Step-by-step explanation:
Let's call the amount of kilograms of lobster K and then formulate equations based on the problem information:
The price in Lobster Foods is L = 18 + 7*K
The price in Megan's Lobster is M = 17 + 8*K
To know how much kilograms of lobster will make both prices be the same, we just need to equate both equations:
L = M
18 + 7*K = 17 + 8*K
8*K - 7*K = 18 - 17
K = 1
The weight of the lobster is 1 kilogram, and Alexa will pay 18 + 7*1 = $25 for the dinner.