So, lets try go to the order of operations. PEMDAS (Parenthesis, Exponent, Multiplication and Division, Addition and Subtraction).
So, going from left to right, 10^5 is simply 1 with 5 zeros, so 100000. Multiply that with 6.11 and we get 611,000. Then, 10^4 is 1 with 4 zeros, so 10000. Multiply that with 2.3 and we get 23,000. Then, it's just a matter of subtraction. 611,000-23,000 = 588,000.
Hope this helps!