Look at this monthly budget.

\begin{tabular}{|l|l|}
\hline & \multicolumn{1}{|c|}{Budgeted} \\
\hline Net income & [tex]$\$[/tex]600$ \\
\hline Total income & [tex]$\$[/tex]600$ \\
\hline Rent & [tex]$-\$[/tex]300$ \\
\hline Train pass & [tex]$-\$[/tex]30$ \\
\hline Total fixed & [tex]$-\$[/tex]330$ \\
\hline Food & [tex]$-\$[/tex]100$ \\
\hline Clothing & [tex]$-\$[/tex]40$ \\
\hline Discretionary & [tex]$-\$[/tex]50$ \\
\hline Total variable & [tex]$-\$[/tex]190$ \\
\hline Savings & [tex]$\$[/tex]80$ \\
\hline
\end{tabular}

Next month, Tokuji's monthly net income will increase to [tex]$\$[/tex]650[tex]$. If he increases his savings to $[/tex]\[tex]$110$[/tex] a month, how much can he increase his discretionary spending?

A. [tex]$\$[/tex]20$
B. [tex]$\$[/tex]10$
C. [tex]$\$[/tex]40$
D. [tex]$\$[/tex]30$



Answer :

Let's analyze Tokuji's current and future budget step-by-step to determine the possible increase in discretionary spending.

### Current Month's Budget

1. Net Income: \$600
2. Total Income: \$600

3. Fixed Expenses:
- Rent: \$300
- Train pass: \$30

Total Fixed Expenses: \[tex]$300 + \$[/tex]30 = \$330

4. Variable Expenses:
- Food: \$100
- Clothing: \$40
- Discretionary: \$50

Total Variable Expenses: \[tex]$100 + \$[/tex]40 + \[tex]$50 = \$[/tex]190

5. Savings: \$80

To calculate the initial discretionary spending, we subtract the fixed expenses, variable expenses, and savings from the net income:
[tex]\[ \text{Discretionary Spending Initial} = \[tex]$600 - (\$[/tex]330 + \[tex]$190 + \$[/tex]80) \][/tex]
[tex]\[ \text{Discretionary Spending Initial} = \[tex]$600 - \$[/tex]600 = \$0 \][/tex]

### Next Month's Budget

Next month, Tokuji's net income will increase to \[tex]$650, and his savings will increase to \$[/tex]110. The fixed and variable expenses remain the same.

1. Net Income: \$650

2. Fixed Expenses (same as before):
- Rent: \$300
- Train pass: \$30

Total Fixed Expenses: \$330

3. Variable Expenses (same as before):
- Food: \$100
- Clothing: \$40

Total Variable Expenses: \[tex]$100 + \$[/tex]40 = \$140

4. Savings: \$110

To calculate the discretionary spending for the next month, we subtract the fixed expenses, variable expenses, and savings from the net income:
[tex]\[ \text{Total Expenses Next} = \[tex]$330 + \$[/tex]140 + \$110 \][/tex]
[tex]\[ \text{Total Expenses Next} = \$580 \][/tex]
[tex]\[ \text{Discretionary Spending Next} = \[tex]$650 - \$[/tex]580 \][/tex]
[tex]\[ \text{Discretionary Spending Next} = \$70 \][/tex]

### Increase in Discretionary Spending

To find the increase in discretionary spending:
[tex]\[ \text{Increase in Discretionary Spending} = \[tex]$70 - \$[/tex]50 = \$20 \][/tex]

Thus, Tokuji can increase his discretionary spending by \$20.

### Conclusion

Out of the given choices:
- \$20
- \$10
- \$40
- \$30

The correct answer is \$20.