Conditional evaluation

[stsxbel]

It does not work for me like this:

    a1 =  float(result1[0] * 0.1)
    b1 =  float(row[2]) #row2- 1продукт
    silos1a = b1 - a1
if silos1a < 0
    print ("Расход:"f'{silos1a:.1f}')
else b1 - 6553.5 - a1
    print ("Расход:"f'{silos1a:.1f}')

SyntaxError: invalid syntax