The equations have the same solution, which means you can convert one into the other by applying rules. To prove this, let's get rid of the fractions by multiplying the first equation by 12 (this number I chose by multiplying the denominators we want to get rid of).
[tex]12 \cdot \frac{2}{3}x + 12\cdot \frac{3}{4} = 12 \cdot 8 \implies[/tex]
[tex]8x + 9 = 96[/tex]
Now move the 9 to the other side:
[tex]8x = 96 - 9 = 87[/tex]
