The a's and b's are confusing me!
For a), I have deduced that g(x) would be something like $-x+a$ where $a$ = the output of $f(x)$... but then you couldn't write g(x) in terms of x and a... ...so how do I write $h(x)$ from this information?
so f(x) has the point (b,a) and g(x) has the points (0,a) and (a,0)... confusing to me...
$g$ is a straight line with gradient $-1$, and $y$ intercept $a$, so its equation is $g(x)=a-x$. $f$ looks like a quadratic, with minimum at $(0,0)$ and a point at $(b,a)$, so $f(x)=\frac{ax^2}{b^2}$. Do you think you can compute the compositions from this?