In an open economy, the marginal propensity to save (mpsmpsmps) is 0.08, the marginal rate of tax (mptmptmpt) is 0.10, and the marginal propensity to import (mpmmpmmpm) is 0.07.

If the government increases public sector investment by £135 billion, what is the resulting final increase in national income (GDP)?
£33.7533.7533.75 billion
£180180180 billion
£540540540 billion
£101.25101.25101.25 billion