On a winters day, the average temperature during the daytime is 40°F. At night the temperature falls to 24°F. What is the percentage decrease?

40%

Step-by-step explanation:

so first we can calculate what percentage of 40 24 is

we can do that with 24/40 which equals 0.6, or 60 percent

100-60

that means that there was a 40 percent decrease.