LAB $7-4$ What's Missing:

The program in this lab should display the average electric bill. Start your $C_{++}$ development tool, and view the Lab$7-4.$cpp file, which is contained in either the Cpp$8\backslash$Chap$07\backslash$Lab$7-4$ Project folder or the Cpp$8\backslash$Chap$07$ folder. $($Depending on your C$++$ development tool, you may need to open Lab$7-4\text{'}$s project$/$solution file first.$)$ Put the $C++$ instructions in the proper order, and then determine the one or more missing instructions. Test the program using the following monthly electric bills: $124\mathrm{.}89,110\mathrm{.}65,99\mathrm{.}43,100\mathrm{.}35,$ and $-1($the sentinel value$).$