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let $S_1,S_2,S_3$ the areas of the shaded area in order from left to right: $S_1=\frac{2.2}{2}=2 ; S_2=\frac{2.6}{2}=6 ; S_3=\frac{6.6}{2}=18$ $\implies S_1+S_2+S_3=2+6+18=26$

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