Given that there are 90 grams of an element that is changing exponentially and, three hours later, there are 120 grams:

A. Find the function, f(t), that models the scenario. Answer format: f(t)=a(b/c)^g/h*t where a,b,c,g and h are constants and base is NOT e. Fully reduce fractions.

B. How much of the element is left after 6 total hours have elapsed? Include units.