Explicação passo-a-passo:
a) 21x-17=109
21x=109+17
x=[tex]\frac{126}{21}[/tex]= 6
b) 73x+100=53x
73x-53x=-100
20x=-100
x=[tex]\frac{-100}{20}[/tex]=-5
c) 1,7+2,5x=4,2
2,5x=4,2-1,7
x=[tex]\frac{2,5}{2,5}[/tex]= 1
g) 10(x+1)-5(x-2)=70
10x+10-5x+10=70
5x=70-20
x=[tex]\frac{50}{5}[/tex]=10
j) 3(x+1)-2(x-1)=-(x+5)
3x+3-2x+2=-x-5
x+5=-x-5
2x=-10
x=[tex]\frac{-10}{2}[/tex]=-5
