Answer:
(a) $3 billion
(b) -$1 billion
Explanation:
All are in terms off billion
Y = 20
T = 2 Â
C = 15
I = 2
we know that Y = C + I + G Â
20 = 15 + 2 + G Â
20 - 17 = G Â
G = 3 Â
So the value of the goods and services purchased by the government of Yokovia = 3 billion
Public saving = T - G Â
            = 2 - 3
            = - 1 billion