7.1) \(\dfrac{64}{(2\sqrt8)^2}\); 7.2) \(\dfrac{360}{(2\sqrt{10})^2}\); 7.3) \(\dfrac{160}{(2\sqrt5)^2}\); 7.4) \(\dfrac{220}{(2\sqrt5)^2}\); 7.5) \(\dfrac{54}{(3\sqrt2)^2}\).

Используем правило: \((a\sqrt b)^2=a^2b\).

1. 7.1: \(64\div(4\cdot8)=64\div32=2\).
2. 7.2: \(360\div(4\cdot10)=360\div40=9\).
3. 7.3: \(160\div(4\cdot5)=160\div20=8\).
4. 7.4: \(220\div(4\cdot5)=220\div20=11\).
5. 7.5: \(54\div(9\cdot2)=54\div18=3\).

Ответ: 7.1) 2; 7.2) 9; 7.3) 8; 7.4) 11; 7.5) 3.