Final answer:
To find out the equation for the spending money (S) that the student has, one must consider the components of national income accounting, such as taxes, government spending, private savings, and investments.
Step-by-step explanation:
The equation for the spending money (S) a student has given the context can be understood through an exercise in macroeconomics. In macroeconomic analysis, particularly in regard to national income accounting and equilibrium, the components such as taxes (T), government spending (G), investment (I), imports (M), and exports (X) play significant roles. The equation described in Step 3 and Step 4, which references private domestic savings (S) and investment (I), provides the grounds for addressing the student's question. According to these steps, the equation is S = 500 + (T - G) - 500. After plugging the appropriate values, the equation may simplify to reflect the level of spending money (S) the student has over time (t).