415 + d ≥ 500
I believe that's the inequality since they want to raise a minimum of $500 so that means it can be more than $500. Hope I helped.
Answer:
20 gallons were used from the tank with the octane rating of 80.
Step-by-step explanation:
Given : One tank of gasoline has an octane rating of 140 and another tank of gasoline has an octane rating of 80. To obtain a mixture of 60 gallons with an octane rating of 120.
To find : How many gallons should be used from the tank with the octane rating of 80?
Solution : Let x be the volume of gas whose octane rating is 140 and
y be the volume of gas whose octane rating is 80.
Then, we form the equation as:
(1) 

or
.........[3]
(2) 
Now multiply equation (2) by 4
...........[4]
Subtract (4) from (3)



Put x in equation [4] we get,





Therefore, x=40 and y=20
So, 20 gallons were used from the tank with the octane rating of 80.
Answer:
We are given that 4 lb of candies are bought for $9.00
Therefore, the price of 1 lb of candies is:

Now the amount of candies that can bought for $12.00 is:
lb
Therefore, 5.3333 lb of candies can be bought for $12.00
we can see that
the above curve is parabola
so, firstly , we can find vertex
vertex is (4,0)

now, we can use vertex formula of parabola

we can plug h and k
and we get

so, we can factor it as
............Answer