its an economics query and I'm confused about what theyr asking and what should be appropriate answer

An economy is operating with output that is $40 billion below its natural level, and fiscal policymakers want to close this recessionary gap. The central bank agrees to adjust the money supply to hold the interest rate constant, so there is no crowding out. The marginal propensity to consume is 4/5, and the price level is completely fixed in the short run. In what direction and by how much would government spending need to change to close the recessionary gap? Explain your thinking