7a - 3b + c - 2d - (3a - 5b + c + 2d)
= 7a - 3b + c - 2d - 3a + 5b - c - 2d
Arrange the polynomial with like terms together and combine them.
= (7a - 3a) + (- 3b + 5b) + (c - c) + (- 2d - 2d)
= 4a + 2b - 4d
Hence, 7a - 3b + c - 2d - (3a - 5b + c + 2d) = 4a + 2b - 4d.