Let the amount of work be $$x$$.
Now $$A$$ does the work in $$25$$ days.
$$\therefore $$ In $$1$$ day $$A$$ does $$\dfrac { x }{ 25 } $$ work,
$$B$$ does the work in $$20$$ days.
$$\therefore $$ In $$1$$ day $$B$$ does $$\dfrac { x }{ 20 } $$ work,
$$C$$ does the work in $$24$$ days.
$$\therefore $$ In $$1$$ day $$C$$ does $$\dfrac { x }{ 24 } $$ work.
$$A$$ works for $$(2+3)$$ days $$=5$$ days.
$$\therefore $$ In $$5$$ days $$A$$ does $$5\times \dfrac { x }{ 25 } $$ work $$=$$ $$\dfrac { x }{ 5 } $$ work,
$$B$$ works for $$2$$ days.
$$\therefore $$ In $$5$$ days $$B$$ does $$2\times \dfrac { x }{ 20 } $$ work= $$\dfrac { x}{ 10 } $$ and
$$C$$ works for $$\left( 2+8\dfrac { 3 }{ 5 } +3 \right) $$ days= $$\dfrac { 68 }{ 5 } $$days.
$$\therefore $$ In $$\dfrac { 68 }{ 5 } $$ days $$C$$ does $$\dfrac { 68 }{ 5 } \times \dfrac { x }{ 24 } $$ work=$$\dfrac { 17x }{ 15 } $$ work.
$$\therefore $$ The total work done by $$A, B$$ and $$C$$, so far $$=$$ $$\dfrac { x }{ 5 } +\dfrac { x }{ 10 } +\dfrac { 17x }{ 13 }$$ work $$=$$ $$\dfrac { 13x }{ 15 } $$ work.
$$\therefore $$ The work left $$=$$ $$x-\dfrac { 13x }{ 15 } $$ work
This work is done by $$D$$ in $$3$$ days.
$$\therefore $$ $$D$$ will finish the whole i.e $$x$$ work in $$3\times \dfrac { 15 }{ 2 } $$days $$=$$$$22\dfrac { 1 }{ 2 } $$ days.
Ans- Option D.