Trouble with IF Statement

I am trying to incorporate two functioning formulas into one.

The formula I was using and works is:

=(([Cost based on Rate] @row - [Deductible Remaining] @row) * [Co-ins% or Co-pay$]@row) + [Deductible Remaining] @row

However, that doesn't account for if the Co-insurance% or Co-pay$ field is blank. So I made this formula that works:

=IF(ISBLANK([Co-ins% or Co-pay$]@row), [Cost based on Rate] @row - [Deductible Remaining] @row, "false")

I combined them this way but it's not working:

=IF(ISBLANK([Co-ins% or Co-pay$]@row), [Cost based on Rate] @row - [Deductible Remaining] @row, (([Cost based on Rate] @row - [Deductible Remaining] @row) * [Co-ins% or Co-pay$]@row) + [Deductible Remaining] @row)

Any help is appreciated!