Need Help on Formula date add & calculation

I am having problem creating formula :

1. Date Add
{custrecord_project_summary_start_date} type : Date
{custrecord_project_summary_duration} type : Integer

formula for estimate end date : TO_CHAR({custrecord_project_summary_start_date}+TO_NUMBER({custrecord_project_summary_duration}),'MM/DD/YYYY')

have tried using Type : "Free form text" and "date"

2. Calculation
{custrecord_mto_volume} type : decimal
{custrecord_mto_price} type : currency

formula for total amount : {custrecord_mto_volume} * {custrecord_mto_price}
using Type : "Currency"

the problem is those two formula isn't showing the result.

any advice?

Thanks,

Andry