The mass of how many grains is 100 grams if the mass of 40 grains is 5 grams.

Let’s solve the problem using the proportion method.
The weight of 40 seeds is 5 grams. Let’s take for X the number of grains with a mass of 100 grams. Let’s write the proportion:
40 seeds correspond to 5 g.
X seeds correspond to 100 g.
40 / X = 5/100
To solve the resulting proportion, we use the “cross” rule: “The product of the extreme terms of the proportion is equal to the product of the middle terms.” Let’s write:
40 × 100 = X × 5
X = (40 × 100) / 5 = 4000/5 = 800 seeds.
Answer: The mass of 800 grains is equal to 100 grams.