Answer
a) $-0.44$
b) $0.51$
c) $f+g=0.07x+24.76$
Slope: $0.07$
Work Step by Step
$f(x)=-0.44x+13.62$
$g(x)=0.51x+11.14$
The functions above models the profit in millions of dollars, $x$ years after $2008$ from each store
a) The slope of $f$ is $-0.44$ and it models that, with each consecutive year after $2008$, the profit decreases by $0.44$ million dollars.
b) The slope of $g$ is $0.51$ and it models that with each consecutive year after $2008$, the profit increases by $0.51$ million dollars.
c) $f+g=(-0.44x+13.62)+(0.51x+11.14)=0.07x+24.76$
The slope is $0.07$ and it models that with each consecutive year after $2008$ the Total profit of the department store increases by $0.07$ million dollars.
