What is the branch of mathematics that uses variables and operations?

The temperature of chicken soup is 192.7°f. as it cools, the temperature of the soup decreases 2.3°f per minute. what is the temperature in degrees fahrenheit of the soup after 25 minutes? a. 27.3°f b. 57.5°f c. 135.2°f d. 250.2°f

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

The radius of a sphere is 3 inches. which represents the volume of the sphere?