Question

7a+5b-c+2a+3b-4c+21a+17b+5c​

Answer 1

$\sf \Large Solution!!$

7a + 5b - c + 2a + 3b - 4c + 21a + 17b + 5c

Group the like terms.

7a + 2a + 21a + 5b + 3b + 17b - c - 4c + 5c

30a + 25b (-5c + 5c = 0; we don't need to put it in the answer.)