Answer:
5.9× 10^4
Explanation:
I'm assuming that by "104" you actually meant "10^4," which reads "fourth power of 10." Please be sure to use the symbol " ^ " to express exponentiation.
The sum of 2.5 × 10^4 and 3.4 × 10^4 is (2.5 + 3.4)×10^4
or
5.9× 10^4