CAT 2022 Functions — Previous Year Question

Suppose for all integers $x$, there are two functions $f$ and $g$ such that $f(x) + f(x-1) - 1 = 0$ and $g(x) = x^2$. If $f\left(x^2 - x\right) = 5$, then the value of the sum $f(g(5)) + g(f(5))$ is