Katrina drinks 0.5 gallons of water per day which expression shows how to find the number of cups of water she drinks in a week or 16 cups in a gallon

Well we know that 1/2 a gallon (or 0.5 gallons) is equal to 8 cups. So one gallon is 16 cups. (keep this in the back of your mind)

Now to find how many cups she drinks in a day, find out how many gallons she drinks in a week.

So 0.5 (7) = 3.5

Now compute to see how many cups are in 3.5 gallons. 

56.0001

Understand?

I’m not absolutely sure but i think it’s 7x6x5x4x3x2=5040 because as the first character you can take any of the 7 given then you are left with 5 then 6 then 4 etc.