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I need help filling in the reasoning that justifies each step

I need help filling in the reasoning that justifies each step-example-1
User INS
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Since angleCDE is equal to x and angleEDF is 3x+20, we have


x-(3x+20)=180

Now, by distributing the minus sign into the parenthesis (Distributive property) we have


x-3x-20=180

By combining similar terms (Addition property), we get


-2x-20=180

By adding 20 to both sides (Inverse property of addition), we obtain


\begin{gathered} -2x-20+20=180+20 \\ \text{then} \\ -2x=200 \end{gathered}

Finally, by multiplying both side by -1/2 (Inverse property of Multiplication), we get


\begin{gathered} (-(1)/(2))*-2x=-(1)/(2)*200 \\ (-2)/(-2)x=-100 \\ x=-100 \end{gathered}

Then, x is equal to -100

User Lalit Verma
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