What’s the arc length of a semi circle with 9 radius

What is the y intercept of f(x)=(1/2)^x?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a. m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class