The calculation form doesn't work

ive been following the instructions but it seems that the calculator is not working

the form name is how much to build an app

we are trying to show the results when  they select the options 

but after following the instructions the form still doesnt show they results.

I checked your calculation setup and I can see that you're calculating the first 2 fields. The only issue is that you've added an extra + symbol at the end which isn't necessary. I removed it and your calculation is now working. Please check it again.