Fiscal balance - Mock B Afternoon

CFA Level I Economics
#1

Hi all,

In the question #31 within the 2020 CFA Level I Mock Exam B: Afternoon Session. It is said:

"In a country with a high level of income, as domestic income rises, it is most likely that an increase will occur in: private saving and investment.

In a country with a high level of income, as domestic income rises, private saving and investment will increase."

However, it doesn’t make much sense to me:

if the formula is (G-T) = (S-I) - (X-M)

Then, if national income increase, T increases, and (G-T) will decrease.

Which means, that expression (S-I) - (X-M) needs to decrease as well.

For that to happen, either (S-I) needs to decrease of (X-M) needs to increase

So I don’t see how “private saving and investment will increase”. According to the above, it should decrease.

Any ideas?

Thanks