We have 23deg in column A and 36min in column B

Converting 23deg 36 min to decimal is straight forward, we put in C =A+B/60, result 23.60

But if it is minus as in -23deg 36min the result is -22.40

Even making ABS(23)+36/60 results 23.60

How do we get the correct value -23.60 in column C ?

Martin