Formula:

Celsius = (Fahrenheit - 32) * 5/9

Calculations:

* 70°F: (70 - 32) * 5/9 = 38 * 5/9 = 21.1°C

* 80°F: (80 - 32) * 5/9 = 48 * 5/9 = 26.7°C

Therefore, 70°F to 80°F is approximately 21.1°C to 26.7°C.