(a) Rs 12500.
Let the loan taken be Rs x. Then,
\(\frac{x\times{6}\times1}{100}+\frac{x\times6.5\times1}{100}+\frac{x\times7\times1}{100}+\frac{x\times7.5\times1}{100}= 3375\)
⇒ \(\frac{27x}{100} = 3375 \) ⇒ x = \(\frac{3375\times100}{27}\) = Rs 12500.