Step-by-step explanation:
Step 1: Subtract the first part
[tex]1\frac{1}{2} - \frac{1}{4}[/tex]
[tex]\frac{3}{2} - \frac{1}{4}[/tex]
[tex]\frac{6}{4}-\frac{1}{4}[/tex]
[tex]\frac{5}{4}[/tex]
Step 2: Multiply both to get how much the brother drank
[tex]\frac{5}{4} * \frac{2}{5}[/tex]
[tex]\frac{2}{4}[/tex]
[tex]\frac{1}{2} \ L[/tex]
Answer: 1/2 Liters
