Google Sheets Editing/ Google Form creation

Need my google formula fixed. a= b x c . b must be a whole number and c cannot be more than 7.875. A is the only data i enter. formula works that has been created but needs to be edited slightly.
Also i need some decimals to be changed to fractions to nearest 1/8th .

Then i would like a google form created when my customers can order from and it automatically transfers into my google sheet