Sam's laptop have a lesser mass because if you turn 4.2kg to grams which is 4200 and compare it to Fred's laptop mass (4950g) you can easily see that Sam's laptop has less.
sam's because his is 4.2g but freds is 4940 and that's a bigger number
Sam's laptop has a mass of 4200 grams and Fred's laptop has a mass of 4940 grams. Since 4200 grams is less than 4940 grams, Sam's laptop is lighter. Therefore, Sam's laptop has less mass.
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