Let's break down the expression step by step:

Solve -2b(-3):
-2b -3 = 6b

Solve 125/5:
125/5 = 25

Put it together: 6b * 25 = 150b

Solve -75b:
-75b

Finally, put it all together: 150b -75b = 75b

So, the simplified expression is 75b.