Answer: There are 30 gallons of anti freeze of first brand and 120 gallons of anti freeze of second brand.
Explanation:
Since we have given that
Percentage of anti freeze in first brand = 35%
Percentage of anti freeze in second brand = 85%
Percentage of anti freeze in mixture = 75%
Total number of gallons of mixture = 150 gallons
We will use " Mixture and Allegation":
First brand Second brand
35% 85%
75%
------------------------------------------------------------------
85%-75% : 75%-35%
10 : 40
1 : 4
So, Number of gallons of anti freeze in first brand is given by

Number of gallons of anti freeze in second brand is given by

Hence, there are 30 gallons of anti freeze of first brand and 120 gallons of anti freeze of second brand.