Let $A be the cost of $q of merchandise under plan A and similarly $B under plan B.
A=120+0.80q, B=40+0.90q
When A=B, 120+0.80q=40+0.90q, 80=0.10q, q=80/0.10=$800.
So you would need to buy $800 of merchandise.
A=B=120+640=40+720=$760 for each plan.
Because K is the midpoint of JL and JK = 18, KL must also equal 18. So the equation would be 3x - 15 = 36 because you add 18 + 18. You then add 15 to both sides to get 3x = 51. Then you divide by 3 on both sides to get x = 17.
20 imperial gallons = 90.9218 litres
so i'd say you'd need to buy 91 bottles or...
20 US Liquid gallons = 75.7082 litres
so you'd have to buy 76 bottles.
Hope this answers your question! It depends what gallon you're working from.
Mean is another word for average add all the values and divide by the numbers in the set
