Tanya and Tashu invested in scheme offering simple interest at the rate of 12% and 15% per annum for 4 years and 3 years respectively. If the amount invested by Tanya is Rs.300 less than the amount invested by Tashu, Find the amount invested by Tashu, if interest received by both of them is equal.

The correct answer is Rs.4800 (Option 4).

Step 1: Understand the given information.
Let the amount invested by Tashu be $T$ rupees.
Since the amount invested by Tanya is Rs. 300 less than that of Tashu, Tanya's investment is:

$\text{Tanya's Investment}=T-300$

Step 2: Note the details of Simple Interest for both investments.
Simple Interest (SI) formula:

$\text{SI}=\frac{P\×R\×t}{100}$

For Tanya:
Principal ($P_1$) = $T-300$
Rate ($R_1$) = 12% per annum
Time ($t_1$) = 4 years

For Tashu:
Principal ($P_2$) = $T$
Rate ($R_2$) = 15% per annum
Time ($t_2$) = 3 years

Step 3: Equate the interest received by both.
It is given that the interest received by both Tanya and Tashu is equal:

$\frac{(T-300)\×12\×4}{100}=\frac{T\×15\×3}{100}$

Step 4: Solve for $T$.
Cancel out 100 from both denominators:

$(T-300)\×48=T\×45$

Expand the left side:

$48T-14400=45T$

Rearrange to group the terms containing $T$:

$48T-45T=14400$

$3T=14400$

$T=\frac{14400}{3}=4800$

Thus, the amount invested by Tashu is Rs. 4800.