Final answer:
To increase GDP by $1200, the government should increase spending by $1500.
Step-by-step explanation:
To increase the GDP by $1200, we can use the formula:
G = (Change in GDP) / (MPC)
Given that the MPC is 0.80, the change in GDP is $1200, so we can plug these values into the formula:
G = $1200 / 0.80 = $1500
Therefore, to increase the GDP by $1200, the government should increase spending by $1500.