Weight of 9 sheets of the paper = 30 g
ie No of sheets of paper in 30 g = 9
No of sheets of paper in 1g = 9/30
= 0.3
1 ¼ kg = 1.25 kg = 1250 g
No of sheets of paper in 1250 g = 0.3 * 1250
= 375 sheets
If the weight of five sheets of paper is 20g how many sheets of the same paper would weigh 2.5kg?