A train journey is approximately 150 miles. How many centimetres will it be on a map with a scale of 30 miles = 1 cm?

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