Which algebraic expression represents the phrase seven more than half of a number

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

Which is the completely factored from of xy^3-x^3y

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?