Rashmi has a road map with a scale of 1 cm representing 18 km. She drives on a road for 72 km. What would be her distance covered in the map?

Case 1: In scale, length of the road map (x1) = 1 cm
Actual distance (y1) = 18 km
Case 2: Let, In scale, length of the road map (x2) = ?
Actual distance (y2) = 72 km
Since, if the length of the road map increases, the corresponding actual distance will also increase. Hence, it is in direct proportion.
→x1/y1 = x2/y2
→1 cm/18 km = x2/72 km
→1 cm/(18 × 72) = x2
→x2 = 4 cm