Complex sentence: As exports increase there is an increase in the income of all persons associated with the exports industries.These in turn create demand for goods.But this is dependent upon their marginal propensity to save (MPS) and marginal propensity to import (MPM).
Split into simpler sentences: As exports increase there is an increase in the income of all persons associated with the exports industries. These increases in income in turn create demand for goods, dependent upon their marginal propensity to save (MPS) and marginal propensity to import (MPM).