==========================================================
Explanation:
The jump from 30 miles to 150 miles is "times 5", meaning 30*5 = 150.
So we need to multiply both sides of the equation
30 miles = 1 cm
by 5 and we get
5*(30 miles) = 5*(1 cm)
150 miles = 5 cm
--------------------
Another way to solve:
This involves proportions
Let x be the distance on the paper map that corresponds to 150 miles
(150 miles)/(x cm) = (30 miles)/(1 cm)
150/x = 30/1
150*1 = x*30 .... cross multiply
150 = 30x
30x = 150
30x/30 = 150/30 ... divide both sides by 30
x = 5 cm is the distance on the paper map