convert function help plese

I am trying to use this function and it is throwing error, i tried it two different ways but getting two different errors, any ideas...

First:
 
Cast(CAST(e.currentintrate as varchar(20))* CAST(e.currentprinbal as varchar(20)) * (30))/((360)*(100))) as VARCHAR(50)) as AINTINC,
Msg 1035, Level 15, State 10, Line 22 
Incorrect syntax near 'Cast', expected 'AS'.
 
Second:
 
convert(varchar, Cast((AINTRATE*AAVGBALA*(30))/((360)*(100)) as  money)) as AINTINC,
 
Msg 8117, Level 16, State 1, Line 9
Operand data type varchar is invalid for multiply operator.

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