How to solve this using definite integral? I already have asked $2$ questions on similar topics. In that questions I have equations of parabola and line. And equations have $y$ and $x$ variable.
But in this question I have functions.
$$f(x) = |x| - 1 \quad\mbox{and}\quad g(x) = 1 - |x|.$$
a) Sketch their graphs.
b) Using integration find the area of the bounded region. 
In other two questions I know how to find values of $x$ and $y$ using substitution. But in this question because of $f(x)$ and $g(x)$. I am clueless how to start.
Please provide answer in detail.
My attempt is only.
$f(x) = x - 1, -x - 1$
$g(x) = 1 - x, 1 + x$.

I presumed you know how to sketch the region. Then
$$A=2\int_{0}^1[(1-x)-(x-1)]dx=\int_0^1(4-4x)dx=2.$$
In set notation, the region $R$ is given by
$$R=\{(x,y):-1\leq x\leq 1,f(x)\leq y\leq g(x)\}.$$
The line $x=0$ or known as the $y$-axis serves the line of symmetry.
Okay,this is the graph of the region $R$.
