To solve this problem, let's go through the step-by-step calculations:
1. Determine the initial budget scenario:
- Net Income: [tex]$600
- Total Fixed Expenses:
- Rent: $[/tex]300
- Train pass: [tex]$30
- Total Fixed: $[/tex]330
- Total Variable Expenses:
- Food: [tex]$100
- Clothing: $[/tex]40
- Discretionary: [tex]$50
- Total Variable: $[/tex]190
- Savings: [tex]$80
2. Calculate the total initial expenses:
\[
\text{Total initial expenses} = \text{Total Fixed} + \text{Total Variable} + \text{Savings} = 330 + 190 + 80 = 600
\]
3. Calculate the discretionary spending:
The discretionary amount is the money left after all fixed, variable expenses, and savings, but since the sum of expenses equals the net income, the current discretionary amount available is zero.
4. New budget scenario:
- Increased Net Income: $[/tex]650
- Fixed expenses remain the same: [tex]$330
- Variable expenses remain the same: $[/tex]190
- Increased Savings: [tex]$110
5. Calculate the new total expenses:
\[
\text{New total expenses} = \text{Total Fixed} + \text{Total Variable} + \text{Increased Savings} = 330 + 190 + 110 = 630
\]
6. Calculate the new discretionary amount:
\[
\text{Discretionary next month} = \text{New Net Income} - \text{New total expenses} = 650 - 630 = 20
\]
7. Calculate the increase in discretionary spending:
The current discretionary amount available is $[/tex]0.
[tex]\[
\text{Increase in discretionary spending} = \text{Discretionary next month} - \text{Current discretionary amount} = 20 - 0 = 20
\][/tex]
Thus, Tokuji can increase his discretionary spending by \$20. Therefore, the correct answer is:
[tex]\[
\boxed{20}
\][/tex]
