Multiply by B2 if B2>0, if not, multply by #

Hi I want to set up a formula to multiply a column a by the value in column b, unless the value in column b is 0, in which case I want to multiply by 30.

Is there a way to do this?


a b c
Row 1 25 0 formula
2 15 0 formula
3 23 13 formula

Many thanks,

=if(b1=0,a1*30,a1*b1)

thanks. this worked.