I have problems trying to construct a proper framework to deal with this one. Please help if you can!

A random sample of 500 registered voters in a rural city is asked if they favor abolition of road tax. If more than 400 voters respond positively, we will conclude that at least 60% of the voters favor the abolition of road tax.

a) Find the probability of Type 1 error if exactly 60% of the voters favor the abolition of road tax.

b) What is the type II error probability if 75% of the voters favor the abolition of road tax?

Thanks!