Conditional evaluation

[stsxbel]

Good day. Please tell me how to correctly compute with the condition? there is a code:

a1 = float(result1[0] * 0.1)
b1 = float(row[2])
c1 = b1 - a1
print (f'{c1:.lf}')

How to make a condition if c = negative value, then write to the database, if positive, then use the formula:

с1 = b1 - 6553.5 - a1

and write the result to the database