Given the word problem, we can deduce the following information:
1. The first brand is 35% pure antifreeze, and the second brand is 60% pure antifreeze.
2. The chemical company intended to obtain 60 gallons of a mixture that contains 45% pure antifreeze.
To determine the amount in gallons of each brand of antifreeze, we first let:
x= the amount of 35% pure antifreeze
60-x= the amount of 60% pure antifreeze
Based on the given information, our equation would be:

Next, we get the value of x:

Then, we plug in x=36 into 60-x:

Therefore,
First brand = 36 gallons
Second brand = 24 gallons