#1: Look at the ratio: 100/240 = (100+150)/x. Solve for x.
100*x = 240 (100+150)
100*x = 240 (250)
x = (240*250)/100
x = 24 * 25 (zeros cancel)
Then you know that 25 * 4 = 100, and you have to take the 4 back out, so 24/4 = 6.
Last: 100 * 6 = 600 meters (m)