The final amount ₹12000 earned when a certain sum P is invested for 7 years on simple interest at x% per annum and the final amount ₹14800 earned when a certain sum P is invested for 7 years on simple interest at (x + 4)% per annum. Find the value of x.
1
\(\frac{40}{7}\)%
2
\(\frac{20}{7}\)%
3
\(\frac{12}{7}\)
4
\(\frac{15}{7}\)%