this is a table with some questions and i don't know how to solve it

Question

-------------table--------------------
(1)real domestic output (GDP=DI) in billions
$200
$250
$300
$350
$400
$450
$500
$550
(2)aggregate expenditures private closed economy billions
$240
$280
$320
$360
$400
$440
$480
$520
(3)exports billions
$20
$20
$20
$20
$20
$20
$20
$20
(4)imports billions
$30
$30
$30
$30
$30
$30
$30
$30
(5)net exports private economy
--
--
--
--
--
--
--
--
(6)aggregate expenditures open,billions
--
--
--
--
--
--
--
--
--
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the 1st question is use columns 1 and 2 to determine the equilibrium GDP for this hypothetical economy.
2.fill in columns 5 and 6 to determine the equilibrium GDP for the open economy.
3. Given the original $20 billion level of exports, what would be the equilibrium GDP if imports were $10 billion greter at each level of GDP?
4. What is the multiplier in this example?