I need help with these two exercises. Thanks

EX 10-9 Depreciation by two methods OBJ. 2 A computer system acquired on January 1 at a cost of $35,000 has an estimated useful life of five years. Assuming that it will have no residual value, determine the depreciation for each of the first two years (a) by the straight-line method and (b) by the double-declining- balance method.EX 10-10 Depreciation by two methods OBJ. 2 A storage tank acquired at the beginning of the fiscal year at a cost of $61,000 has an estimated residual value of $9,000 and an estimated useful life of 20 years. Determine the following: (a) the amount of annual depreciation by the straight-line method and (b) the amount of depreciation for the first and second years computed by the double-declining- balance method