Is this the whole question? If so, this how I found my answer(I do not know if this is the answer 100% and I won't and can't take credit for the answer being incorrect. It is your choice to go with my answer, thank you.):
A restaurant can seat 100 people. Okay, the capacity is 100. Got it. It has booths that seat 4 people. Okay! So I am going to represent B"Booths" as "B". A variable. B = 4. Okay, let's continue. And, it has tables that seat 6 people. I will represent "Tables" as T. So, T = 6!
Alllrighty then, let's get to the nit and grit..
B = 4 T = 6
In the last sentence, it says, 5 of the booths are full, what expression matches the situation? Well, it's ONLY asking for the expression, so that's all we'll give.
We don't need the "table" variable because it's asking about the booths so, bye bye tables. B = 4, and 5 of them are full. We would have to do B(5) or B * 5. B equals 4 so 4 * 5 which equals 20. The expressions we could use are:
B(5) = 20
or
4 * 5 = 20
or
20 = 4 * 5 = B(5)
I hope this answer helps you out! Bye! :)
