Resposta :
4(x+5)+3(x+5)=21
4x+20+3x+15=21
4x+3x+20+15=21
7x+35=21
7x=21-35
7x=-14
x=-14/7
x=-2
4x+20+3x+15=21
4x+3x+20+15=21
7x+35=21
7x=21-35
7x=-14
x=-14/7
x=-2
Equações do 1° Grau ..
4(x+5)+3(x+5)= 21