Since $$12 \div \frac{3}{4}=16$$, the actual distance between the towns is $$16\times10 = 160$$ miles. 
The scale of a map is:~$\dfrac{3}{4}$ of an inch $$=10$$ miles. If the distance on the map between two towns is $$12$$ inches, the actual distance between the towns is． 
$$90$$ miles 
$$120$$ miles 
$$150$$ miles 
$$160$$ miles 