what is the formula to calculate the asset of a investment, by equity or cost method? thanks. cost+net income-dividend? if so, why need to subtract dividend? Thanks.

you are basically accounting for the portion of the company that you have a stake in. if that company earns X amount and then pays of Y amount = the total value add is X-Y so you basically do the same in your balance sheet . You take your total investment in the company (the price you paid) + your portion of Net Income - your portion of div income