Sandy mixed together 5 gallons of one brand of juice and 4 gallons of a second brand of juice, which contains 70 percent real fruit juice. Find the percent of real fruit juice in the first brand if the mixture contained 40 percent real fruit juice. Which of the following equations could be used to solve this?

14%
Step-by-step explanation:
Let the percent of the real fruit in the first brand = x
Given that number of gallons of real fruit in the first brand = 9 gallons
Given that percent of the real fruit in the second brand = 48%
Given that number of gallons of real fruit in the second brand = 8 gallons
Given that percent of the real fruit in the mixture = 30%
then number of gallons of real fruit in the mixture = (9+8) = 17 gallons
Then we get equation:
[x% of 9 gallons] + [48% of 8 gallons] = [30% of 17 gallons]
9x+48(8)=30(17)
9x+384=510
9x=510-384
9x=126
x=126/9
x=14
Hence final answer is 14%