#### Answer

$10$

#### Work Step by Step

Absolute value is used to represent the distance of a number from $0$ on a number line. Since distances are always positive, the result of an absolute value will always be positive. Therefore, to take the absolute value of a negative number, we simply take the negative of that number to make it positive, and to take the absolute value of a positive number, we do nothing to the number.
We start with the given expression: $2|-21+16|$
We simplify inside the absolute value symbols by adding: $2|-5|$
We take the negative of the negative inside of the absolute values to make it positive: $2(-(-5))=2(5)$
We multiply: $10$