Question

Subtract +6p+q+3r+8 from p-2q-5r+6

Answer 1

(p-2q-5r+6) - (+6p+q+3r+8)
The second brackets terms changes in its signs:
p - 2q - 5r + 6 - 6p -q -3r - 8
-5p -3q -8r -2 (Answer).

Answer 2

p-2q-5r+6 -6p-q-3r-8
p-6p-2q-q-5r-3r+6-8
-5p-3q-8r-2