To subtract numbers in scientific notation, we have to bring both to same powers of 10.
Let's change the first number to 10 to the power 8.
So, it will become:
[tex]2.53\times10^5=0.00253\times10^8[/tex]So, we have to perform:
[tex]1.3\times10^8-0.00253\times10^8[/tex]Now we simply perform the subtraction and tag along 10 to the power 8.
So,
1.3 - 0.00253 = 1.29747
So, answer is:
[tex]1.29747\times10^8[/tex]