Answer :

Benjamin16
[tex]r=20-27=-7 \\ \\ a_{1}=27 \\ \\ a_{n}=a_{1}+(n-1)r \\ \\ -36=27+(n-1)*(-7) \\ \\ -7(n-1)=-63 \\ \\ n-1=9 \\ \\ n=10 \\ \\ S_{10}= \frac{27-36}{2}*10=-9*5=-45 [/tex]

\\\ Ben

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