Given:
Let x be the amount of 65% pure antifreeze.
Let (30-x) be the amount of 95% pure antifreeze.
We need to obtain 30 gallons of mix fixture that contains 85% pure antifreeze.
To find the number of gallons in each brand:
According to the question,
Let us frame the equation,
[tex]65\text{ \% (x)+9}5\text{ \% (30-x)}=85\text{ \% (30)}[/tex]
On simplification we get,
[tex]\begin{gathered} \frac{65}{100}\times x+\frac{95}{100}\times(30-x)=\frac{85}{100}\times(30) \\ \frac{65x+95(30-x)}{100}=\frac{85(30)}{100} \\ 65x+95(30-x)=85(30) \\ 65x+2850-95x=2550 \\ -30x=2550-2850 \\ -30x=-300 \\ x=10 \end{gathered}[/tex]
Therefore,
The amount of 65% pure antifreeze needed is 10 gallons.
The amount of 95% pure antifreeze needed is 20 gallons.