Let x = volume of 20% solution=0.2
Let y = volume of 30% solution=0.3
Equation of total volume:
x + y = 90
Equation of amount of acid:
[tex]\begin{gathered} 0.2x+0.3y=0.25(90) \\ 0.2x+0.3y=22.5 \\ Solve\text{ x+y = 90 , for x} \\ x=90-y \end{gathered}[/tex]
Substitute into the second equation
[tex]\begin{gathered} 0.2(90-y)+0.3y=22.5 \\ 18-0.2y+0.3y=22.5 \\ 0.1y=22.5-18 \\ 0.1y=4.5 \\ \text{divide both side by 0.1} \\ \frac{0.1y}{0.1}=\frac{4.5}{0.1} \\ y=45 \\ \sin ce\text{ x=90-y} \\ x=90-45 \\ x=45 \end{gathered}[/tex]
Therefore 45 liters of 20% solution and 45 liters of 30% solution
Hence the volume of 20% acid = 45 litres
the volume of 30% acid = 45 litres
