Correct Answer: 75 days

Solution : Let the time T takes to complete the work = $x$ days
⇒ the time T takes to complete half of the work = $\frac{x}{2}$ days
⇒ So, S will take to complete half of the work = $\frac{1}{8x}$
So, $\frac{\text{Efficiecncy of T}}{\text{Efficiency of S}}=\frac{\text{Time taken by S}}{\text{Time taken by T}}$
= $\frac{\frac{1}{8x}}{\frac{x}2}$
= $\frac{1}{4}$
Together they complete the work in 60 days,
⇒ Total work = 60 × (1 + 4) = 300 units
S will take to finish the whole work = $\frac{300}4$ = 75 days
Hence, the correct answer is 75 days.