Can sage be used to solve the following kind of problem?

edit

You can just use the following script to do it. You construct two functions f and g such that they have a slope of 5 and 4 respectively and add a constant such that f(1) = 9 and g(9)=6 then evaluate at 1.05 using g(f(1.05)).

f(x)=5*x+4
g(x)=4*x-30
g(f(1.05))