Assume there is no discretionary increase in government spending. Explain how an improving economy will affect the budget balance and, in turn, investment and the trade balance.

The budget balance refers to the difference between government revenues (taxes) and government expenditures (spending). A budget surplus occurs when revenues exceed spending, while a budget deficit occurs when spending exceeds revenues. Investment refers to the purchase of new capital goods (like equipment and machinery) by businesses in order to produce goods and services more efficiently. Investment helps improve productivity and economic growth. The trade balance, also known as the net exports, is the difference between the value of a country's exports (goods and services it sells to other countries) and the value of imports (goods and services it buys from other countries). If the value of exports is higher than the value of imports, the trade balance is said to be in surplus. Conversely, if the value of imports is higher than the exports, then the trade balance is in deficit.

An improving economy usually means an increase in national income, employment, and output. As the economy improves, people's incomes also increase, leading to higher tax revenues for the government. Additionally, an improving economy can result in lower government spending on certain items, such as unemployment benefits, as more people find jobs. This leads to a decrease in government expenditures. With higher tax revenues and lower expenditures, the budget balance can move towards a surplus. A budget surplus means the government can either reduce its level of borrowing or even pay off its existing debts. As a result, more funds become available for private investment. This can encourage businesses to invest in new capital goods.

An improving economy can also affect the trade balance. As people's incomes rise, they tend to consume more goods and services – both domestically produced and imported. This increase in imports can potentially cause a trade deficit, provided that exports do not rise proportionately. On the other hand, the increase in investment due to the improving economy can lead to an increase in productivity and competitiveness of domestic industries. This, in turn, can boost exports. If the increase in exports is greater than the increase in imports, the trade balance can move towards a surplus. In summary, an improving economy without a discretionary increase in government spending can lead to a budget surplus and boost investment. However, its effect on the trade balance depends on the relative changes in the values of imports and exports.