secondary 4 chevron_right E Maths chevron_right Singapore

I am not sure if my answer is correct. The answer key has this solution:
Let $x be sum of money But invested. Amount of money in the account at the end of 4 years
= $x(1 + 2.5/100)^4
= $1.103812x
$1.103812x = $x + $674.79
1.103812x - x = 674.79
x = 6500.115594
Sum of money But invested in the account = $6500.12 (nearest cent)

But instead of evaluating the amount in the start, I do it later on... so can my answer still be correct?