Answer the question on the basis of the following information for a private closed economy.
S = -20 + .4Y
Ig = 25 - 3i
where S is saving, Ig is gross investment, i is the real interest rate, and Y is GDP.

Refer to the above information. In equilibrium the level of saving will be:
A) $10.
B) $15.
C) $20.
D) $30.