Sally has 4.5 cups of sugar. She needs to bake brownies for for a bake sale. If each batch of brownies requires 2/3 cup of sugar, how many batches of brownies can she make?
4.5 / 0.667 = ?
To determine how many batches of brownies Sally can make, we need to divide the total amount of sugar she has (4.5 cups) by the amount of sugar required per batch (2/3 cup).
To do this, we can use division. We divide 4.5 by 2/3:
4.5 ÷ (2/3)
To divide fractions, we multiply the first fraction by the reciprocal (flipped version) of the second fraction:
4.5 × (3/2)
Now, it's easier to multiply fractions if we convert the whole number to a fraction:
4.5 = 4 1/2, which is the same as (9/2)
Substituting into the calculation:
(9/2) × (3/2)
To multiply fractions, we multiply the numerators (top numbers) and denominators (bottom numbers):
(9 × 3) / (2 × 2) = 27/4
So, Sally can make 27/4 or 6.75 batches of brownies.
However, we can't have a fraction of a batch, so we need to round down to a whole number. Sally can make 6 batches of brownies.