Priya lent $\text{Rs. }3,500$ to her friend at a simple interest rate of $6\%$ per annum. After how many years will the interest amount to $\text{Rs. }1,050$?

The formula for Simple Interest ($\text{SI}$) is:
$$\text{SI}=\frac{P\times R\times T}{100}$$

Given:

* Principal ($P$) = $\text{Rs. }3,500$
* Rate ($R$) = $6\%$
* Simple Interest ($\text{SI}$) = $\text{Rs. }1,050$

Substitute the given values into the formula to calculate Time ($T$):

$$1050=\frac{3500\times 6\times T}{100}$$

$$1050=35\times 6\times T$$

$$1050=210\times T$$

Solve for $T$:

$$T=\frac{1050}{210}=5\text{years}$$