Step 1: Total Fertilizer-P = 2520 / 0.21 = 12000 Kg. Total Fertilizer-Q = 3150 / 0.21 = 15000 Kg.
Step 2: Fertilizer-P sale of A, B, C = (15 + 22 + 21)% of 12000 = 58% of 12000 = 6960 Kg.
Step 3: Fertilizer-Q sale of C, D, E = (30 + 10 + 17)% of 15000 = 57% of 15000 = 8550 Kg.
Step 4: Difference = 8550 minus 6960 = 1590 Kg.