So for the first one, you want to look at the ratio;
1 cm : 2 m and 1 cm : 4 m
This means that for every 2 meters you would draw one centimeter, or every 4.
Drawing B is the larger drawing because it uses a larger number of meters.
The second one is almost like the first, except for every 10 meters you draw 1 centimeter. 50 divided by 10 is 5 and 25 divided by 10 is 2.5 These are the centimeters.
Draw 5 cm for the length and 2.5 cm for the width.