Using a calculator, you can find out that [tex]\sf{ \frac{4}{7}\approx 0.571428571 \approx.571[/tex]
and so that means [tex]\sf{ 7\frac{4}{7}\approx 7.571428571 \approx 7.571[/tex]
so your answer is
[tex]\sf{ 7\frac{4}{7} \approx \huge{\boxed{7.571}}[/tex]