You have the following number given in the exercise:
According to the information given in the exercise, the digit 4 (located in the ten thousands place) was changed to a 7. Then now it is:
In order to find how much the value would change, you must find the difference (the difference, by definition, is the result of a subtraction).
In this case, knowing the value of the digits, you can set up the following subtraction:
Solving the subtraction, you get the following difference:
Therefore, the answer is: