Explanation
Concept:
The area between the curves y1=f(x) and y2=g(x) is given by:
Area enclosed = ∫x2x1(y1 - y2)dx
Where, x1 and x2 are the intersections of curves y1and y2
Calculation:
Shaded area has to be calculated
Curve 1:y=∣x−1∣
⇒ y = 1 - x for x < 1
⇒ y = x - 1 for x ≥ 1
Curve 2:y=3−∣x∣
⇒ y = 3 + x for x < 0
⇒ y = 3 - x for x ≥ 0

\begin{aligned}
& \mathrm{Area~enclosed~(A)=\int_{x_{1}}^{x_{2}}(y_{1}-y_{2})dx} \\
& \Rightarrow\mathrm{A}=\int_{-1}^{2}3-|\mathrm{x}|-|\mathrm{x}-1|\mathrm{dx} \\
& \Rightarrow\mathrm{A=\left|\int_{-1}^{0}3+x-(1-x)dx\right|+\left|\int_{0}^{1}3-x-(1-x)dx\right|+\left|\int_{1}^{2}3-x-(x-1)dx\right|} \\
& \Rightarrow\mathrm{A=\left|\int_{-1}^{0}(2+2x)dx\right|+\left|\int_{0}^{1}2dx\right|+\left|\int_{1}^{2}(4-2x)dx\right|} \\
& \Rightarrow\mathrm{A=\left|[2x+x^{2}]_{-1}^{0}\right|+\left|[2x]_{0}^{1}\right|+\left|[4x-x^{2}]_{1}^{2}\right|} \\
& \Rightarrow\mathrm{A=1+2+1=4~sq.~units}
\end{aligned}