Answer:
c. $76.17 billion
Step-by-step explanation:
The relations between imports, exports, and tariffs can be described by ...
0.06E +0.21I = $18.9603 . . . . . . total tariff revenue
I -E = 26.76 . . . . . . . . . . . . . . . . trade deficit
Solving the second equation for E gives ...
E = I -26.76
Substituting into the first equation yields ...
0.06(I -26.76) +0.21I = 18.9603
0.27I = 18.9603 +1.6056 = 20.5659 . . . . add 1.6056 to both sides
I = 10.5659/0.27 = 76.17
Romania's imports are worth about $76.17 billion.
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Additional comment
The exports are worth about $76.17 -26.76 = $49.41 billion.