Cost as on 01.04.2016 = Rs.28,000/0.70 = Rs. 40,000
A. Total Depreciation under Old Method = Rs.40,000 - Rs.28,000 = Rs.12,000
B. Total Depreciation under New Method = Rs.40,000 -[40,000 × 90%, × 90% × 90%] = Rs.10,840
C. Excess Depreciation to be written back Rs.1,160