Answer: Leticia won the first round
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Your teacher is basically asking "which value is further from zero on the number line?". The value -19 is 19 units away from zero; while 21 is 21 units away from zero.
See the attached image below. Each "space" is a distance of 1
Absolute value measures distance along the number line. Distance is never negative. In terms of notation, you would say
|-19| = 19 and |21| = 21
The outputs 19 and 21 are then compared. We see that 21 is larger, so therefore, Leticia has the higher score and she won the first round.
