Explanation:
(a)
y = 6x
with each can she can make 6 cups. so the number of cups is 6 times the number of cans.
(b)
there are 16 cups in a gallon.
in 10 gallons there are then 10×16 = 160 cups.
how many cans of frozen lemonade concentrate does she need to make 160 cups ?
we use the equation from (a) :
160 = 6x
x = 160/6 = 80/3 = 26.66666... cans
now, the cans are only sold in packs of 4.
so, she needs 26.66666.../4 = 6.666666... packs.
therefore, we need to round to the next whole number.
that means she needs to buy 7 packs.