shootingstar

I'm reading page 144 of SN (econ):

They are saying that base currency appreciation will cause exports to decrease and imports to increase, thus decreasing aggregate demand.

Based on the AD formula: AD= C + I + G + (X-I) ,

They must be assuming that X will decrease more than the increase in I otherwise they would offset and AD would be unchanged. Opposite is true for base currency depreciation.

What is the logic behind this assumption that X is affected more by currency appreciations/depreciations than I?