Verified Answer :

apologiabiology

distribute
a(b+c)=ab+ac
2(10-r)=20-2r

now we have
8+20-2r
28-2r

JMatney

8 + 2(10 - r)
Distribute: 2(10 - r)

8 + 20 - 2r
Evaluate: 8 + 20

Convert: -2r + 28

-2r + 28

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