Question

12 PONTOS! 4(X+5)+3(X+5)=21
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Answer 1

4(x+5)+3(x+5)=21 
4x+20+3x+15=21 
7x+35=21 
7x=21-35 
7x= -14 
x= -14/7 
x= -2 

Answer 2

$4(x+5)+3(x+5)=21 \\ \\ \\ 4x+20+3x+15=21 \\ \\ 4x+3x=21-20-15 \\ \\ 7x=21-35 \\ 7x=-14 \\ \\ x= \frac{-14}{7} \\ \\ x=-2$