Can someone plz help me with this math question the test is due tomorrow (50 points)

Aheated piece of metal cools according to the function c(x) = (.5)x ? 7, where x is measured in hours. a device is added that aids in cooling according to the function h(x) = ? x ? 2. what will be the temperature of the metal after two hours?

7. if the value of x varies directly with the value of y, and x = 3 when y = 21. what is the valu y, and x = 3 when y = 21. what is the value of x when y = 105?

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5