It worked in this version:
a1 = float(140.2) b1 = float(6543.5) silos1a = b1 - a1 if silos1a > 0: print(f'Расход: {silos1a:.1f}') else: silos1a = b1 - 6553.5 - a1 print(f'Расход: {silos1a:.1f}')