Best friends, Olivia and Sylvia both get a weekly allowance. Olivia and Sylvia’s allowance are in the ratio of 2 to 3 if Sylvia gets $21 one week how much did Olivia get?

If the ratio of Olivia's allowance to Sylvia's allowance is 2:3, then Olivia gets 2/3 of what Sylvia gets.

If Sylvia gets $21, then Olivia gets 2/3 * $21 = $<<2/3*21=14>>14. Answer: \boxed{14}.

To find out how much Olivia got, you can set up a proportion based on the ratio of their allowances.

The ratio of Olivia's allowance to Sylvia's allowance is 2:3, which can also be written as 2/3.

Since Sylvia got $21, we can set up the proportion:

2/3 = x/21

To solve for x (the amount Olivia got), we can cross-multiply:

(2 * 21) = (3 * x)
42 = 3x

To find the value of x, divide both sides of the equation by 3:

42/3 = x
14 = x

Therefore, Olivia got $14.

To find out how much Olivia got, we can use the concept of ratios.

Given that the ratio of Olivia's allowance to Sylvia's allowance is 2 to 3, we can set up the equation:

2/3 = Olivia's allowance / Sylvia's allowance

Since we know Sylvia's allowance is $21, we can substitute that value into the equation:

2/3 = Olivia's allowance / $21

To isolate Olivia's allowance, we can cross-multiply:

2 * $21 = 3 * Olivia's allowance

$42 = 3 * Olivia's allowance

To find Olivia's allowance, we can divide both sides of the equation by 3:

$42 / 3 = Olivia's allowance

Olivia's allowance would be $14.