Question

$21b - 32 + 7b - 20b$

Answer 1

21b-32+7b-20b
1b+7b-32
8b-32
8(b-4)
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thank u

Answer 2

28b-32-20b=0
8b-32=0
8b=32
b=32/8
b=4

This is your answer...