Hi I want a cell to return two different results depending on what is
entered. For example I want a function in column C (Outstanding) that will
either return the value of Col A (PO value) or it will return the difference
when a value is entered in col B ( Inv Value)

PO Value Invoice Value Outstanding

£1,417.05 1441.26 -£24.21
£635.21 319.37 £315.84

Any help here would be appreciated. Thanks